// do we no longer want a callback for when the closing sequence begins
public void RemoveClosingSequenceEndCallback(ClosingSequenceEndDelegate callback)
{
_onClosingSequenceEnd -= callback;
}
// do we want a callback for when the closing sequence end
public void AddClosingSequenceEndCallback(ClosingSequenceEndDelegate callback)
{
RemoveClosingSequenceEndCallback(callback); // avoid duplicate addition
_onClosingSequenceEnd += callback;
}