isTurtle check

src/kernel/turtle/Turtle.hx

@@ -18,7 +18,7 @@ class Turtle {
 	}
 
 	public static function isTurtle():Bool {
-		return true; // TODO: Implement
+		return cc.Turtle != null;
 	}
 
 	private function conterToOutcome(r:cc.Turtle.TurtleActionResult):Outcome<Noise, String> {