code: def set_field(self, name, value, parse=False):
          
          # explicit getitem needed for ValueField
          try: 
              item = dict.__getitem__(self, name)
              item.set( item.parse(value) if parse else value  )
          except ValidationError as err:
              raise FieldValidationError(name, value, list(err))
docs: Set the value of a field