docs: def trigger(self, username, project, branch, **build_params):
          """Trigger new build and return a summary of the build."""
          method = 'POST'
          url = ('/project/{username}/{project}/tree/{branch}?'
                 'circle-token={token}'.format(
                     username=username, project=project,
                     branch=branch, token=self.client.api_token))
  
          if build_params is not None:
              json_data = self.client.request(method, url,
                                              build_parameters=build_params)
          else:
              json_data = self.client.request(method, url)
          return json_data