def METHOD_NAME(
    self, classes: List[Class], module_namespace: Optional[str]
) -> str:
    """Render the source code of the classes."""
    load = self.env.get_template
    def render_class(obj: Class) -> str:
        """Render class or enumeration."""
        if obj.is_enumeration:
            template = load("enum.jinja2")
        elif obj.is_service:
            template = load("service.jinja2")
        else:
            template = load("class.jinja2")
        return template.render(
            obj=obj,
            module_namespace=module_namespace,
        ).strip()
    return "\n\n\n".join(map(render_class, classes)) + "\n"