<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def decorate_event_js(js_code):
 """setup a method as an event, adding also javascript code to generate Args: js_code (str):
 javascript code to generate the event client-side. js_code is added to the widget html as widget.attributes['onclick'] = js_code%{'emitter_identifier':widget.identifier, 'event_name':'onclick'} """

    def add_annotation(method):
        setattr(method, "__is_event", True )
        setattr(method, "_js_code", js_code )
        return method
    return add_annotation