//var chx = this.getChildAt(0)
//var chy = this.getChildAt(1)
//var chz = this.getChildAt(2)
//this.removeChildAt(1)
//chx === this.getChildAt(0)
true
//chz === this.getChildAt(1)
true
//this.numChildren
2
//this.removeChildAt(0)
//chz === this.getChildAt(0)
true
//this.numChildren
1
//this.removeChildAt(0)
//this.numChildren
0
