'Remove a previously added trigger callable.
@param handle: An object previously returned by L{addTrigger}.  The
trigger added by that call will be removed.
@raise ValueError: If the trigger associated with C{handle} has already
been removed or if C{handle} is not a valid handle.'

def removeTrigger(self, handle):

    return getattr(self, ('removeTrigger_' + self.state))(handle)
