This is what I have so far. I want the rectangle to move back to the other side instead of the just stopping. Another variable needs to be used for this but I don't know how. Could someone help please?

1. int xp = 100;
   
   void setup() {
   
     size(300, 300);
     noStroke();
   }
   
   
   void draw() {
     background(0,0,0);
     rect(xp, 100, 10, 10);
     xp++;
     if (xp > width-10) {
       xp = width-10;  
   }
   
    
     println(xp);
   }