code: function push(arr){
    var i, len = arr.length;
    this.added || (this.added = {});
    for(i=0;i<len;i++){
      arr[i].markDirty();
      if(this.added[arr[i].cid]) continue;
      this.added[arr[i].cid] = 1;
      this.push(arr[i]);
    }
  }
docs: Push all elements in `arr` to the end of an array. Mark all Computed Properties as dirty on their way in.