code: def _flat_columns_in_table(self, table):
          
          for col in self._get_dbt_columns_from_bq_table(table):
              flattened = col.flatten()
              for subcol in flattened:
                  yield subcol
docs: An iterator over the flattened columns for a given schema and table.
          Resolves child columns as having the name "parent.child".