Swagger.io has a feature that it can build a complete client from any API definition file (YAML or url).
First, open a new browser window and go to https://editor.swagger.io/ (there is no need to have an user for this).
Then go to File, Import File:
A window will open, browse for the YAML file with the API specs and then press "Open":
The file will load and you will be able to see its contents on the screen:
Besides the operations you can do with Swagger, there is a menu on top that allows you to generate a Client in any of the software languages that the application support:
Once you select on one of the options, a client file will be quickly generated and you will be able to download it to your PC:
Once you open the zip file, you will find the source code of the client that was generated by the webapp:
You can use the generated code as a sample of the source code for the local implementation of the REST API that you need to develop.
Before implementing any code downloaded from internet, check first if it works and also if it complies with the IT requirements of your Office (regulations, licenses and security).