void setup () {
 size (100,100);
 background (0);
 stroke (100,50,255);
 strokeWeight (20);
 smooth ();

 }

 int mrX = 0;

 void draw (){

   background (0);
   point (mrX,75 );
   mrX = mrX + 2;
   point (mrX,25);

   if (mrX > 400){

     mrX = 0;

   }
 }