def __call__(self, inst, attr, value):
        """
        We use a callable class to be able to change the ``__repr__``.
        """
        if self.mapping_validator is not None:
            self.mapping_validator(inst, attr, value)

        for key in value:
            self.key_validator(inst, attr, key)
            self.value_validator(inst, attr, value[key])

        We use a callable class to be able to change the ``__repr__``.
        
product/gradle-plugin/src/main/python/attr/validators.py