Call when exiting a directive node in the ast.

def leave_Directive(self, node, *args):
        """Call when exiting a directive node in the ast."""
        name_to_arg_value = {
            # Taking [0] is ok here because the GraphQL parser checks for the
            # existence of ':' in directive arguments.
            arg.split(':', 1)[0]: arg
            for arg in node.arguments
        }

        ordered_args = node.arguments
        directive = DIRECTIVES_BY_NAME.get(node.name)
        if directive:
            sorted_args = []
            encountered_argument_names = set()

            # Iterate through all defined arguments in the directive schema.
            for defined_arg_name in six.iterkeys(directive.args):
                if defined_arg_name in name_to_arg_value:
                    # The argument was present in the query, print it in the correct order.
                    encountered_argument_names.add(defined_arg_name)
                    sorted_args.append(name_to_arg_value[defined_arg_name])

            # Get all the arguments that weren't defined in the directive schema.
            # They will be printed after all the arguments that were in the schema.
            unsorted_args = [
                value
                for name, value in six.iteritems(name_to_arg_value)
                if name not in encountered_argument_names
            ]

            ordered_args = sorted_args + unsorted_args

        return '@' + node.name + wrap('(', join(ordered_args, ', '), ')')