code: def reserve_ids(self, resource, num_ids):
          
          return self.service.reserve_ids(
              resource, num_ids,
              self.url_prefix, self.auth, self.session, self.session_send_opts)
docs: Reserve a block of unique, sequential ids for annotations.
  
          Args:
              resource (intern.resource.Resource): Resource should be an annotation channel.
              num_ids (int): Number of ids to reserve.
  
          Returns:
              (int): First id reserved.