boxgames1 · June 29, 2018 11:25
diff --git a/BinaryTreePreorder.js b/BinaryTreePreorder.js
 preorder(node, fn) {
  if (node !== null) {
    fn(node);
    this.preorder(node.left, fn);
    this.preorder(node.right, fn);
  }
 }
	preorder(node, fn) {
	if (node !== null) {
	fn(node);
	this.preorder(node.left, fn);
	this.preorder(node.right, fn);
	}
	}