code: def convert_row(self, keyed_row, schema, fallbacks):
          
          for key, value in list(keyed_row.items()):
              field = schema.get_field(key)
              if not field:
                  del keyed_row[key]
              if key in fallbacks:
                  value = _uncast_value(value, field=field)
              else:
                  value = field.cast_value(value)
              keyed_row[key] = value
          return keyed_row
docs: Convert row to SQL