your code
shuttle(700,700,500);
mothership(100,700);
wall(600,500,600,800);
wall(600,0,600,400);
wall(200,350,600,350);
wall(200,0,200,250);
wall(350,100,600,100);
fuel(700,425,900);
fuel(400,425,800);
fuel(200,275,800);
fuel(300,50,800);
planet(700,50,"earth");
planet(500,425,"mars");
planet(100,300,"venus");
planet(300,200,"neptune");
planet(100,600,"mercury");
planet(400,50,"uranus");
planet(500,250,"jupiter");
alien(200,500,500,500);