Optical fiber routing generation method, device, equipment, medium and computer program product

Abstract

The present invention provides a method, apparatus, device, medium, and computer program product for generating optical fiber routes. The method comprises: obtaining an optical path table and a fiber core table corresponding to a route-related device, wherein the optical path table includes a route start field and a route end field; querying each fiber core table for a first start terminal that matches the route start field to determine a first end terminal corresponding to the first start terminal; if the first end terminal does not match the route end field, querying each fiber core table for a second start terminal that matches the first end terminal to determine a second end terminal corresponding to the second start terminal; if the second end terminal matches the route end field, generating an optical fiber route corresponding to the route-related device based on the first start terminal, the first end terminal, the second start terminal, and the second end terminal. The present invention achieves automatic generation of optical fiber routes by jointly querying the optical path table and the fiber core table to generate optical fiber routes.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber communication technology, and in particular to an optical fiber route generation method, device, equipment, medium and computer program product. Background Art

[0002] After the optical fiber between devices is opened, in scenarios where the fiber core resource data is complex and highly correlated, if the optical fiber route between devices cannot be automatically generated due to the system or other reasons, optical fiber communication between devices cannot be achieved. Therefore, how to automatically generate the optical fiber route between devices in the case of complex and highly correlated fiber core resource data has become a technical problem that needs to be solved urgently. Summary of the Invention

[0003] The present invention provides a method, device, equipment, medium and computer program product for generating optical fiber routes, which are used to solve the technical problem that the existing technical solutions cannot automatically generate optical fiber routes between devices.

[0004] The present invention provides a method for generating an optical fiber route, comprising:

[0005] Obtaining an optical path table and a fiber core table corresponding to a routing-related device, wherein the optical path table includes a routing start point field and a routing end point field;

[0006] Querying the first starting terminal that matches the routing starting point field in each of the core tables, and determining the first ending terminal corresponding to the first starting terminal;

[0007] In the case that the first end terminal does not match the routing end field, querying each of the core tables for a second start terminal that matches the first end terminal, and determining a second end terminal corresponding to the second start terminal;

[0008] When the second end terminal matches the route end field, an optical fiber route corresponding to the route-related device is generated according to the first starting terminal, the first end terminal, the second starting terminal, and the second end terminal.

[0009] According to a method for generating an optical fiber route provided by the present invention, the route-related devices include a route starting device and a route ending device; and obtaining the optical path table and the fiber core table corresponding to the route-related devices includes:

[0010] Generate a routing start point field corresponding to the port of the routing start point device, and a routing end point field corresponding to the port of the routing end point device;

[0011] Determine a lightpath table including the routing start point field and the routing end point field;

[0012] Obtaining a starting terminal and an ending terminal of each fiber core between the routing starting device and the routing ending device;

[0013] A core table including the start terminal and the end terminal corresponding to each of the cores is determined.

[0014] According to a method for generating an optical fiber route provided by the present invention, determining the first end terminal corresponding to the first starting terminal includes:

[0015] A target core table including the first starting terminal is determined in each of the core tables, and an end terminal in the target core table is used as a first end terminal corresponding to the first starting terminal.

[0016] According to a method for generating an optical fiber route provided by the present invention, after determining the first end terminal corresponding to the first starting terminal, the method further includes:

[0017] In a case where the first end terminal matches the routing end field, an optical fiber route corresponding to the routing-related device is generated according to the first starting terminal and the first end terminal.

[0018] According to a method for generating an optical fiber route provided by the present invention, after determining the second end terminal corresponding to the second starting terminal, the method further includes:

[0019] Determine a core type corresponding to the core table including the second starting terminal and the second ending terminal;

[0020] In a case where the fiber core type is a line jumper, it is determined that the second destination terminal matches the routing destination field.

[0021] According to a method for generating an optical fiber route provided by the present invention, after determining the core type corresponding to the core table including the second starting terminal and the second ending terminal, the method further comprises:

[0022] In a case where the fiber core type is an optical cable fiber core, it is determined that the second destination terminal does not match the routing destination field.

[0023] The present invention also provides a fiber routing generating device, comprising:

[0024] An acquisition module is used to obtain an optical path table and a fiber core table corresponding to a routing-related device, wherein the optical path table includes a routing start point field and a routing end point field;

[0025] A first query module is configured to query each of the core tables for a first starting terminal that matches the routing starting point field, and determine a first ending terminal corresponding to the first starting terminal;

[0026] a second query module configured to query each of the core tables for a second starting terminal that matches the first ending terminal when the first ending terminal does not match the routing ending field, and determine a second ending terminal corresponding to the second starting terminal;

[0027] The optical fiber route generating module is used to generate an optical fiber route corresponding to the routing related device according to the first starting terminal, the first ending terminal, the second starting terminal and the second ending terminal when the second ending terminal matches the routing ending field.

[0028] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, any of the above-described methods for generating optical fiber routing is implemented.

[0029] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the optical fiber routing generation method described in any one of the above is implemented.

[0030] The present invention also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the computer program implements any of the above-mentioned methods for generating optical fiber routes.

[0031] The optical fiber route generation method, apparatus, device, medium, and computer program product provided by the present invention obtain an optical path table and a fiber core table corresponding to a routing-related device. The optical path table includes a route start field and a route end field. The method then queries each fiber core table for a first starting terminal that matches the route start field and determines the first end terminal corresponding to the first starting terminal. If the first end terminal does not match the route end field, the method queries each fiber core table for a second starting terminal that matches the first end terminal and determines the second end terminal corresponding to the second starting terminal. If the second end terminal matches the route end field, the method generates an optical fiber route corresponding to the routing-related device based on the first starting terminal, the first end terminal, the second starting terminal, and the second end terminal. By jointly querying the optical path table and the fiber core table to generate an optical fiber route, automatic generation of an optical fiber route is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1This is one of the flow charts of the optical fiber routing generation method provided by the present invention;

[0034] Figure 2 This is the second flow chart of the optical fiber routing generation method provided by the present invention;

[0035] Figure 3 It is a structural diagram of the optical fiber routing generating device provided by the present invention;

[0036] Figure 4 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0038] The following combination Figure 1-Figure 2 The optical fiber route generation method of the present invention is described.

[0039] Please refer to Figure 1 The present invention provides a method for generating an optical fiber route, comprising:

[0040] Step 100: Obtain an optical path table and a fiber core table corresponding to a routing-related device, wherein the optical path table includes a routing start point field and a routing end point field;

[0041] Specifically, the routing-related devices in this embodiment include a routing starting point device and a routing ending point device. The purpose of the optical fiber routing generation method provided in this embodiment is to generate an optical path route between the routing starting point device and the routing ending point device. When the optical path between the routing starting point device and the routing ending point device is opened but the optical path routing data is not generated, the optical path data and the routing starting point field and routing ending point field contained in the optical path table in the optical path data are obtained, wherein the optical path data also includes a fiber core table.

[0042] Step 200, querying the first starting terminal that matches the routing starting point field in each of the core tables, and determining the first ending terminal corresponding to the first starting terminal;

[0043] Specifically, there are multiple optical fibers between the routing starting point device and the routing ending point device (or there may be only one optical fiber), and each optical fiber has its corresponding fiber core table. The fiber core table includes the identification of the corresponding optical fiber, which is used to distinguish different optical fibers. The fiber core table also includes terminal information at both ends of the optical fiber. In this embodiment, the first starting terminal that matches the routing starting point field refers to one end of the first optical fiber connected to the routing starting point device, and the first ending point terminal in this embodiment is the other end of the first optical fiber connected to the routing starting point device. The first starting terminal and the first ending terminal exist in the fiber core table corresponding to the optical fiber connected to the routing starting point device.

[0044] Step 300: If the first end terminal does not match the routing end field, query each of the core tables for a second start terminal that matches the first end terminal, and determine a second end terminal corresponding to the second start terminal.

[0045] Specifically, if the first end terminal does not match the routing end field, it means that the other end of the optical fiber connected to the routing starting point device is not connected to the routing end device, that is, there is more than one first optical fiber between the routing starting point device and the routing end device. When the first end terminal does not match the routing end field, continue to query the second starting terminal that matches the first end terminal in the fiber core table corresponding to each optical fiber, wherein the second starting terminal refers to one end of the second optical fiber connected to the first end terminal, and the second end terminal corresponding to the second starting terminal refers to the other end of the second optical fiber connected to the first end terminal, and the second starting terminal and the second end terminal exist in the fiber core table corresponding to the optical fiber connected to the first end terminal.

[0046] Step 400 : When the second end terminal matches the route end field, generate an optical fiber route corresponding to the route-related device according to the first start terminal, the first end terminal, the second start terminal, and the second end terminal.

[0047] It is understandable that if the second end terminal also does not match the routing end field, it means that the other end of the optical fiber connected to the first end terminal is not connected to the routing end device, that is, there are more than the first optical fiber and the second optical fiber between the routing starting device and the routing end device. If the second end terminal does not match the routing end field, the start terminal that matches the second end terminal in the fiber core table corresponding to each optical fiber is continuously queried until an end terminal that matches the routing end field is found. Then, an optical fiber route containing all the start terminals and end terminals obtained in the above query process is generated. If the second end terminal matches the routing end field, an optical fiber route containing the first start terminal, the first end terminal, the second start terminal, and the second end terminal is generated corresponding to the routing-related device.

[0048] This embodiment obtains the optical path table and fiber core table corresponding to the routing-related devices. The optical path table includes a routing start point field and a routing end point field. The optical path table then queries the first starting point terminal in each fiber core table that matches the routing start point field and determines the first end point terminal corresponding to the first starting point terminal. If the first end point terminal does not match the routing end point field, the optical path table queries the second starting point terminal in each fiber core table that matches the first end point terminal and determines the second end point corresponding to the second starting point terminal. If the second end point matches the routing end point field, the optical fiber route corresponding to the routing-related devices is generated based on the first starting terminal, the first end terminal, the second starting terminal, and the second end terminal. By jointly querying the optical path table and the fiber core table to generate the optical fiber route, the automatic generation of the optical fiber route is achieved.

[0049] Please refer to Figure 2 In one embodiment, the optical fiber route generation method provided in the embodiment of the present application may further include:

[0050] Step 110, generating a routing start point field corresponding to the port of the routing start point device, and a routing end point field corresponding to the port of the routing end point device;

[0051] Step 120, determining a light path table including the routing start point field and the routing end point field;

[0052] Step 130: Obtain the starting terminal and the ending terminal of each fiber core between the routing starting device and the routing ending device;

[0053] Step 140: Determine a core table corresponding to each of the fiber cores, including the start terminal and the end terminal.

[0054] Specifically, it is known that routing-related devices include routing starting devices and routing ending devices. After determining the routing starting device and the routing ending device, the routing starting field corresponding to the port of the routing starting device and the routing ending field corresponding to the port of the routing ending device are generated, and the optical path table containing the routing starting field and the routing ending field is determined, and then the starting terminal and the ending terminal of each fiber core between the routing starting device and the routing ending device are obtained. Finally, the fiber core table containing the starting terminal and the ending terminal corresponding to each fiber core is determined, that is, each optical fiber between the routing starting device and the routing ending device has its corresponding fiber core table.

[0055] This embodiment generates a light path table and a fiber core table by generating route start and end point fields and obtaining the start and end point terminals of the fiber core. By jointly querying the light path table and the fiber core table, the fiber route can be automatically generated, thereby realizing automatic generation of the fiber route.

[0056] In one embodiment, the optical fiber route generation method provided in the embodiment of the present application may further include:

[0057] Step 210: Determine a target core table containing the first starting terminal in each core table, and use the ending terminal in the target core table as the first ending terminal corresponding to the first starting terminal.

[0058] It can be understood that each optical fiber between the routing starting point device and the routing ending point device has its corresponding fiber core table. After determining the target fiber core table containing the first starting point terminal in each fiber core table, the ending point terminal in the target fiber core table can be used as the first ending point terminal corresponding to the first starting point terminal. The first starting point terminal and the first ending point terminal exist in the same fiber core table.

[0059] This embodiment determines that the first starting terminal and the first ending terminal exist in the same fiber core table, which establishes a basis for joint query of the fiber core table and the optical path table.

[0060] In one embodiment, the optical fiber route generation method provided in the embodiment of the present application may further include:

[0061] Step 500: When the first end terminal matches the route end field, generate an optical fiber route corresponding to the route-related device according to the first start terminal and the first end terminal.

[0062] Specifically, if the first end terminal matches the routing end field, it means that the other end of the optical fiber connected to the routing starting point device is connected to the routing end point device, that is, there is only the first optical fiber connected to the routing starting point device between the routing starting point device and the routing end point device. In this case, an optical fiber route including the first starting point terminal and the first end point terminal is generated corresponding to the routing-related device.

[0063] This embodiment generates optical fiber routes by jointly querying the optical path table and the fiber core table, thereby achieving automatic generation of optical fiber routes.

[0064] In one embodiment, the optical fiber route generation method provided in the embodiment of the present application may further include:

[0065] Step 600, determining a core type corresponding to the core table including the second starting terminal and the second ending terminal;

[0066] Step 700: When the fiber core type is a line jumper, determine whether the second destination terminal matches the routing destination field.

[0067] Specifically, the core type of the optical fiber can be determined, and then, based on the core type, whether the optical fiber's end terminal matches the routing end field. After determining the first starting terminal and its corresponding first end terminal, or determining the second starting terminal and its corresponding second end terminal, the core type corresponding to the core table containing the first starting terminal and the first end terminal can be determined, or the core type corresponding to the core table containing the second starting terminal and the second end terminal can be determined. If the core type is a line jumper, the first end terminal is determined to match the routing end field, or the second end terminal is determined to match the routing end field.

[0068] This embodiment determines whether the destination terminal matches the route destination field by the core type of the optical fiber corresponding to the core table, and generates the optical fiber route by jointly querying the optical path table and the core table, thereby realizing automatic generation of the optical fiber route.

[0069] In one embodiment, the optical fiber route generation method provided in the embodiment of the present application may further include:

[0070] Step 800: When the fiber core type is an optical cable fiber core, determine that the second end terminal does not match the routing end field.

[0071] It is understood that after determining the first starting terminal and its corresponding first ending terminal, or determining the second starting terminal and its corresponding second ending terminal, the core type corresponding to the core table containing the first starting terminal and the first ending terminal is further determined, or the core type corresponding to the core table containing the second starting terminal and the second ending terminal is further determined. In the case where the core type is an optical cable core, it is determined that the first ending terminal does not match the routing ending field, or it is determined that the second ending terminal does not match the routing ending field.

[0072] This embodiment determines whether the destination terminal matches the route destination field by the core type of the optical fiber corresponding to the core table, and generates the optical fiber route by jointly querying the optical path table and the core table, thereby realizing automatic generation of the optical fiber route.

[0073] The optical fiber route generation device provided by the present invention is described below. The optical fiber route generation device described below and the optical fiber route generation method described above can be referenced to each other.

[0074] Please refer to Figure 3 The present invention also provides a fiber routing generation device, comprising:

[0075] An acquisition module 301 is configured to acquire an optical path table and a fiber core table corresponding to a routing-related device, wherein the optical path table includes a routing start point field and a routing end point field;

[0076] A first query module 302 is configured to query each of the core tables for a first starting terminal that matches the routing starting point field, and determine a first ending terminal corresponding to the first starting terminal;

[0077] A second query module 303 is configured to query each of the core tables for a second starting terminal that matches the first ending terminal when the first ending terminal does not match the routing ending field, and determine a second ending terminal corresponding to the second starting terminal;

[0078] The optical fiber route generating module 304 is configured to generate an optical fiber route corresponding to the routing-related device according to the first starting terminal, the first ending terminal, the second starting terminal and the second ending terminal when the second ending terminal matches the routing ending field.

[0079] Optionally, the routing-related devices include a routing starting point device and a routing ending point device; and the acquisition module includes:

[0080] A field generating unit, configured to generate a routing start point field corresponding to the port of the routing start point device, and a routing end point field corresponding to the port of the routing end point device;

[0081] A light path table determining unit, configured to determine a light path table including the route start point field and the route end point field;

[0082] A terminal acquisition unit, configured to acquire a start terminal and an end terminal of each fiber core between the routing start device and the routing end device;

[0083] The core table determining unit is configured to determine a core table corresponding to each of the cores, the core table including the start terminal and the end terminal.

[0084] Optionally, the first query module includes:

[0085] The determining unit is configured to determine a target core table including the first starting terminal in each of the core tables, and use the ending terminal in the target core table as the first ending terminal corresponding to the first starting terminal.

[0086] Optionally, the optical fiber routing generating device further includes:

[0087] The optical fiber route generating module is configured to generate an optical fiber route corresponding to the routing related device according to the first starting terminal and the first ending terminal when the first ending terminal matches the routing ending field.

[0088] Optionally, the optical fiber routing generating device further includes:

[0089] a fiber core type determination module, configured to determine a fiber core type corresponding to the fiber core table including the second starting terminal and the second ending terminal;

[0090] The first determining module is configured to determine, when the fiber core type is a line jumper, that the second destination terminal matches the routing destination field.

[0091] Optionally, the optical fiber routing generating device further includes:

[0092] The second determining module is configured to determine, when the fiber core type is an optical cable fiber core, that the second terminal terminal does not match the routing terminal field.

[0093] Figure 4 An example of a physical structure diagram of an electronic device is shown below. Figure 4 As shown, the electronic device may include: a processor 410, a communication interface 420, a memory 430, and a communication bus 440, wherein the processor 410, the communication interface 420, and the memory 430 communicate with each other via the communication bus 440. The processor 410 may call the logic instructions in the memory 430 to execute the optical fiber route generation method.

[0094] In addition, the logic instructions in the above-mentioned memory 430 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0095] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the optical fiber routing generation method provided by the above methods.

[0096] In another aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which is implemented when the computer program is executed by a processor to execute the optical fiber routing generation method provided by the above methods.

[0097] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0098] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, or of course, by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the existing technology can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or certain parts of the embodiments.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for generating an optical fiber route, characterized in that: include: Obtaining an optical path table and a fiber core table corresponding to a routing-related device, wherein the optical path table includes a routing start point field and a routing end point field; Querying the first starting terminal that matches the routing starting point field in each of the core tables, and determining the first ending terminal corresponding to the first starting terminal; In the case that the first end terminal does not match the routing end field, querying each of the core tables for a second start terminal that matches the first end terminal, and determining a second end terminal corresponding to the second start terminal; When the second end terminal matches the route end field, generating an optical fiber route corresponding to the route-related device according to the first starting terminal, the first end terminal, the second starting terminal, and the second end terminal; The step of determining the second end terminal corresponding to the second starting terminal includes: Determine a core type corresponding to the core table including the second starting terminal and the second ending terminal; In a case where the fiber core type is a line jumper, determining that the second destination terminal matches the routing destination field; In a case where the fiber core type is an optical cable fiber core, it is determined that the second destination terminal does not match the routing destination field.

2. The optical fiber routing generation method according to claim 1, characterized in that: The routing-related devices include routing starting point devices and routing end point devices; The obtaining of the optical path table and the fiber core table corresponding to the routing related equipment includes: Generate a routing start point field corresponding to the port of the routing start point device, and a routing end point field corresponding to the port of the routing end point device; Determine a lightpath table including the routing start point field and the routing end point field; Obtaining a starting terminal and an ending terminal of each fiber core between the routing starting device and the routing ending device; A core table including the start terminal and the end terminal corresponding to each of the cores is determined.

3. The optical fiber routing generation method according to claim 2, characterized in that: Determining the first end terminal corresponding to the first starting terminal includes: A target core table including the first starting terminal is determined in each of the core tables, and an end terminal in the target core table is used as a first end terminal corresponding to the first starting terminal.

4. The optical fiber routing generation method according to claim 1, wherein: The step of determining the first end terminal corresponding to the first starting terminal includes: In a case where the first end terminal matches the routing end field, an optical fiber route corresponding to the routing-related device is generated according to the first starting terminal and the first end terminal.

5. A fiber routing generation device, characterized in that: include: An acquisition module is used to obtain an optical path table and a fiber core table corresponding to a routing-related device, wherein the optical path table includes a routing start point field and a routing end point field; A first query module is configured to query each of the core tables for a first starting terminal that matches the routing starting point field, and determine a first ending terminal corresponding to the first starting terminal; a second query module configured to query each of the core tables for a second starting terminal that matches the first ending terminal when the first ending terminal does not match the routing ending field, and determine a second ending terminal corresponding to the second starting terminal; an optical fiber route generating module, configured to generate an optical fiber route corresponding to the routing-related device according to the first starting terminal, the first ending terminal, the second starting terminal, and the second ending terminal, when the second ending terminal matches the routing ending field; The optical fiber routing generating device further includes: a fiber core type determination module, configured to determine a fiber core type corresponding to the fiber core table including the second starting terminal and the second ending terminal; A first determining module is configured to determine, when the fiber core type is a line jumper, whether the second terminal terminal matches the routing terminal field; The second determining module is configured to determine, when the fiber core type is an optical cable fiber core, that the second terminal terminal does not match the routing terminal field.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the optical fiber route generation method according to any one of claims 1 to 4 is implemented.

7. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the optical fiber route generation method according to any one of claims 1 to 4 is implemented.

8. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the optical fiber route generation method according to any one of claims 1 to 4 is implemented.

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