public void setup() {
		
		  background(255);
		  size(300, 300);
		  visited = new boolean[width][height];
		  
		  frameRate(20);
		  step = 15;

		  // Create a walker object and put into an ArrayList
		  for (int i = 0; i < numWalkers; i++){
		  walkers.add(new Walker(this, step));
		  }
		
	}