# This method is a instance method inside the _base.Application class.
def get_xsd(self, model, pretty_print=False):
        schema_entries = _SchemaEntries(self)
        model.add_to_schema(schema_entries)
        nodes = self.__build_schema_nodes(schema_entries, types=None)
        return etree.tostring(nodes[nodes.keys()[0]], pretty_print=pretty_print)