class BSTNode {
  constructor(value) {
    this.value = value;
    this.left = null;
    this.right = null;
  }

  insertLeft(value) {
    let node = new BSTNode(value);
    this.left = node;
    return node;
  }

  inserRight(value) {
    let node = new BSTNode(value);
    this.right = node;
    return node;
  }
}