code: def __SetBaseHeaders(self, http_request, client):
          
          # TODO(craigcitro): Make the default a little better here, and
          # include the apitools version.
          user_agent = client.user_agent or 'apitools-client/1.0'
          http_request.headers['user-agent'] = user_agent
          http_request.headers['accept'] = 'application/json'
          http_request.headers['accept-encoding'] = 'gzip, deflate'
docs: Fill in the basic headers on http_request.