code: def missing_revisions(self, doc_id, *revisions):
          
          url = '/'.join((self.database_url, '_missing_revs'))
          data = {doc_id: list(revisions)}
  
          resp = self.r_session.post(
              url,
              headers={'Content-Type': 'application/json'},
              data=json.dumps(data, cls=self.client.encoder)
          )
          resp.raise_for_status()
  
          resp_json = response_to_json_dict(resp)
          missing_revs = resp_json['missing_revs'].get(doc_id)
          if missing_revs is None:
              missing_revs = []
  
          return missing_revs
docs: Returns a list of document revision values that do not exist in the
          current remote database for the specified document id and specified
          list of revision values.
  
          :param str doc_id: Document id to check for missing revisions against.
          :param list revisions: List of document revisions values to check
              against.
  
          :returns: List of missing document revision values