code: def fetch_request_token(self, oauth_request):
          
          try:
              # Get the request token for authorization.
              token = self._get_token(oauth_request, 'request')
          except Error:
              # No token required for the initial token request.
              version = self._get_version(oauth_request)
              consumer = self._get_consumer(oauth_request)
              try:
                  callback = self.get_callback(oauth_request)
              except Error:
                  callback = None # 1.0, no callback specified.
              self._check_signature(oauth_request, consumer, None)
              # Fetch a new token.
              token = self.data_store.fetch_request_token(consumer, callback)
          return token
docs: Processes a request_token request and returns the
          request token on success.