docs: def extend_with_default(validator_class: Any) -> Any:
      """Append defaults from schema to instance need to be validated.
  
      :param validator_class: Apply the change for given validator class.
      """
      validate_properties = validator_class.VALIDATORS['properties']
  
      def set_defaults(validator: Any,
                       properties: dict,
                       instance: dict,
                       schema: dict) -> Iterator[ValidationError]:
          for prop, subschema in properties.items():
              if 'default' in subschema:
                  instance.setdefault(prop, subschema['default'])
  
          for error in validate_properties(
              validator, properties, instance, schema,
          ):
              yield error  # pragma: no cover
  
      return extend(validator_class, {'properties': set_defaults})