@classmethod
def walk(cls, obj):
    """
        Convert a schema structure into a `JSON Schema <https://json-schema.org>`_ representation.

        Args:
            schema (.Schema):
                Input schema or structure.

        Returns:
            dict:
                Equivalent JSON Schema data.
        """
    schema = super().walk(obj)
    schema['$schema'] = 'http://json-schema.org/schema#'
    return schema
