2 pll

{
[3,
	[2,
		[1,false,false],
		["a",
			false,
			["b",false,false]]],
	["b",
		["xx",false,false],
		false]]


3--"b"
|   |
|  "xx"
|
2--"a"--"b"
|
|
|
1

---------->
1
|
|
|
3--"b"
|   |
|  "xx"
|
2--"a"--"b"


[1,[3,[2,false,["a",false,["b",false,false]]],["b",["xx",false,false],false]],false]
}