code: def list(self, request, *args, **kwargs):
          
          return super(ProjectPermissionViewSet, self).list(request, *args, **kwargs)
docs: Project permissions expresses connection of user to a project.
          User may have either project manager or system administrator permission in the project.
          Use */api/project-permissions/* endpoint to maintain project permissions.
  
          Note that project permissions can be viewed and modified only by customer owners and staff users.
  
          To list all visible permissions, run a **GET** query against a list.
          Response will contain a list of project users and their brief data.
  
          To add a new user to the project, **POST** a new relationship to */api/project-permissions/* endpoint specifying
          project, user and the role of the user ('admin' or 'manager'):
  
          .. code-block:: http
  
              POST /api/project-permissions/ HTTP/1.1
              Accept: application/json
              Authorization: Token 95a688962bf68678fd4c8cec4d138ddd9493c93b
              Host: example.com
  
              {
                  "project": "http://example.com/api/projects/6c9b01c251c24174a6691a1f894fae31/",
                  "role": "manager",
                  "user": "http://example.com/api/users/82cec6c8e0484e0ab1429412fe4194b7/"
              }