docs: def buckets(self):
          """https://github.com/frictionlessdata/tableschema-bigquery-py#storage
          """
  
          # No cached value
          if self.__buckets is None:
  
              # Get response
              response = self.__service.tables().list(
                  projectId=self.__project,
                  datasetId=self.__dataset).execute()
  
              # Extract buckets
              self.__buckets = []
              for table in response.get('tables', []):
                  table_name = table['tableReference']['tableId']
                  bucket = self.__mapper.restore_bucket(table_name)
                  if bucket is not None:
                      self.__buckets.append(bucket)
  
          return self.__buckets