DataSift\Storyplayer\PlayerLib\Story_Checkpoint::isNot PHP Method

is the named property set to false?

public isNot ( string $propName ) : boolean
$propName	string
return	boolean

    public function isNot($propName)
    {
        return !isset($this->{$propName}) || $this->{$propName} != true;
    }

Story_Checkpoint