public static function cancel( ScopedCallback &$sc = null ) {
		if ( $sc ) {
			$sc->callback = null;
		}
		$sc = null;
	}
public static function cancel( ScopedCallback &$sc = null ) {
		if ( $sc ) {
			$sc->callback = null;
		}
		$sc = null;
	}
public static function cancel ( ScopedCallback & $ sc = null ) { if ( $ sc ) { $ sc -> callback = null ; } $ sc = null ; }
Destroy a scoped callback without triggering it.

@param ScopedCallback|null &$sc
Destroy a scoped callback without triggering it .