code: def _authenticate(self, params, headers):
          
          if self.authentication:
              user = self.authentication.get_user()
              params.update({'auth': user.firebase_auth_token})
              headers.update(self.authentication.authenticator.HEADERS)
docs: Method that simply adjusts authentication credentials for the
          request.
          `params` is the querystring of the request.
          `headers` is the header of the request.
  
          If auth instance is not provided to this class, this method simply
          returns without doing anything.