This trigger will fire when a mobile attempts to leave a room. There are
    two modes that are important to distinguish between. The first mode is
    "status only" mode, this means the script should only return true or
    false, and not perform any other actions. The other mode is the actual
    attempt to exit the room. The "status only" mode is usually invoked
    internally by the mud engine to see if the move is viable before
    attempting it. In the other mode if your script prevents exit by returning
    false, then it should also echo some kind of message to the creature
    attempting to leave the room. Your script should hande both modes. The
    following variables are of interest for this trigger:

    @n - The mobile that wants to enter the room.

    @o - The same as @i if the trigger owner is an object.

    @direction  - One of north, south, east, west, up, or down.

    @fromRoom   - The room from which the mobile wants to leave.

    @toRoom     - The room to which the mobile wants to go.

    @statusOnly - 1 for "status only" mode, 0 for normal mode.

    Your script must return a 1 or a 0 (or equivalent). Any value that does
    not evaluate to true, will prevent the mobile from leaving the source
    room.