void setup(){
  size(200,200);
  background(255);
  framerate(30);
}
void draw(){
  smooth();
 int pos=(round(random(50,100))*((round(random(1))*2)-1))+100;
  stroke(random(255),random(255),random(255));
  line(random(50,150),random(50,150),pos,pos);
}