human
Solve the following python programming problem given the following code:
def enable_selfalias(config, id_name) : 
    '
    This allows replacing id_name with "self".
    e.g. /users/joe/account == /users/self/account if joe is in the session
    as an authorized user
    ' 
    def context_found_subscriber(event) : 
        request = event.request 
        user = getattr (request, 'user', None) 
        if (request.matchdict and (request.matchdict.get (id_name, None) == 'self') and user) : 
            request.matchdict [id_name] = user.username 
config.add_subscriber (<MASK>, ContextFound) 
    
    Given the code above, what is a proper replacement for <MASK>? Choose among: id_name, config
assistant
#Here is a proper replacement for <MASK>.
def context_found_subscriber(