code: def _get_fields(self, event, pull, message=None):
          
          result = pull.fields_general(event)            
          if message is not None:
              result["__message__"] = message
              
          return result
docs: Constructs a dictionary of fields and replacement values based on the
          specified event and the status of the pull request.
          
          :arg event: one of ["start", "error", "finish"].
          :arg pull: an instance of PullRequest that has details about the current
            status of the pull request testing etc.
          :arg message: an additional contextual message to add in the __message__ field.