def configure_custom(self, config):
            """Configure an object with a user-supplied factory."""
            c = config.pop('()')
            if not callable(c):
                c = self.resolve(c)
            props = config.pop('.', None)
            # Check for valid identifiers
            kwargs = dict([(k, config[k]) for k in config if valid_ident(k)])
            result = c(**kwargs)
            if props:
                for name, value in props.items():
                    setattr(result, name, value)
            return result
Configure an object with a user-supplied factory.
product/gradle-plugin/src/main/python/pip/_vendor/distlib/compat.py