def parse(self, parser: Parser) -> nodes.Output:
        """Work when something match `tags` variable."""
        lineno = next(parser.stream).lineno
        node = parser.parse_expression()
        call_method = self.call_method('_hello', [node], lineno=lineno)
        return nodes.Output([call_method], lineno=lineno)
Work when something match `tags` variable.
tests/test-extensions/hello_extension/hello_extension.py