code: def describe(self, bucket, descriptor=None):
          
  
          # Set descriptor
          if descriptor is not None:
              self.__descriptors[bucket] = descriptor
  
          # Get descriptor
          else:
              descriptor = self.__descriptors.get(bucket)
              if descriptor is None:
                  table_name = self.__mapper.convert_bucket(bucket)
                  response = self.__service.tables().get(
                      projectId=self.__project,
                      datasetId=self.__dataset,
                      tableId=table_name).execute()
                  converted_descriptor = response['schema']
                  descriptor = self.__mapper.restore_descriptor(converted_descriptor)
  
          return descriptor
docs: https://github.com/frictionlessdata/tableschema-bigquery-py#storage