private function makeCallbackHumanReadable( Callable $callback )
    {
        if( is_string($callback) ) {
            return $callback;
        } elseif( is_array($callback) ) {
            return sprintf(
                "%s::%s",
                is_object( $callback[0] ) ? get_class($callback[0]) : $callback[0],
                $callback[1]
            );
        } elseif( !($callback instanceof \Closure) ) {
            return "<closure>";
        }
        throw new \Exception("Wow. I didn't know php could define a callable of this type. Pete __definately__ wants to know all about this.");
    }