code: def create(self, list_id, data):
          
          self.list_id = list_id
          if 'name' not in data:
              raise KeyError('The list merge field must have a name')
          if 'type' not in data:
              raise KeyError('The list merge field must have a type')
          response = self._mc_client._post(url=self._build_path(list_id, 'merge-fields'), data=data)
          if response is not None:
              self.merge_id = response['merge_id']
          else:
              self.merge_id = None
          return response
docs: Add a new merge field for a specific list.
  
          :param list_id: The unique id for the list.
          :type list_id: :py:class:`str`
          :param data: The request body parameters
          :type data: :py:class:`dict`
          data = {
              "name": string*,
              "type": string*
          }