unshift : function() {
    var orgData = [];
    for (var i = 0; i < this.length; i++){
      orgData[i] = this[i];
    }
    var arr = [];
    for (var i = 0; i < arguments.length; i++){
      if(arguments[i] instanceof Array){
        arr = arr.concat(arguments[i]);
      }else{
        arr.push(arguments[i]);
      }
    }
    arr = arr.concat(orgData);
    for (var i = 0; i < arr.length; i++){
      this[i] = arr[i];
    }
    return this.length;
  },