code: def get_value(self, spec, row):
          
          column = spec.get('column')
          default = spec.get('default')
          if column is None:
              if default is not None:
                  return self.convert_type(default, spec)
              return
          value = row.get(column)
          if is_empty(value):
              if default is not None:
                  return self.convert_type(default, spec)
              return None
          return self.convert_type(value, spec)
docs: Returns the value or a dict with a 'value' entry plus extra fields.