code: def register(self, url, doc):
          
          try:
              self.pid.register()
              # Set metadata for DOI
              self.api.metadata_post(doc)
              # Mint DOI
              self.api.doi_post(self.pid.pid_value, url)
          except (DataCiteError, HttpError):
              logger.exception("Failed to register in DataCite",
                               extra=dict(pid=self.pid))
              raise
          logger.info("Successfully registered in DataCite",
                      extra=dict(pid=self.pid))
          return True
docs: Register a DOI via the DataCite API.
  
          :param url: Specify the URL for the API.
          :param doc: Set metadata for DOI.
          :returns: `True` if is registered successfully.