Return a unicode object with the MATCH representation of this expression.

def to_match(self):
        """Return a unicode object with the MATCH representation of this expression."""
        self.validate()

        mark_name, _ = self.fold_scope_location.get_location_name()
        validate_safe_string(mark_name)

        template = u'$%(mark_name)s.size()'
        template_data = {
            'mark_name': mark_name,
        }
        return template % template_data