text: /**
  Given two binary trees, write a function to check if they are equal or not.
  
  Two binary trees are considered equal if they are structurally identical and the nodes have the same value.
  
   * Definition for binary tree
   * function TreeNode(val) {
   *     this.val = val;
   *     this.left = this.right = null;
   * }
   */
  
  /**
   * @param {TreeNode} p
   * @param {TreeNode} q
   * @returns {boolean}
   */
  var isSameTree = function(p, q) {
      if (!p && !q) {
          return true;
      }
      if (!p || !q) {
          return false;
      }
      if (p.val !== q.val) {
          return false;
      }
      return isSameTree(p.left, q.left)&&isSameTree(p.right, q.right);
  };
  