<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def notify_attached(room, event, user):
 """Notifies about an existing chatroom being attached to an event. :param room: the chatroom :param event: the event :param user: the user performing the action """

    tpl = get_plugin_template_module('emails/attached.txt', chatroom=room, event=event, user=user)
    _send(event, tpl)