Given an array of nodes, LeetCode style, return the plain text version of a binary tree representation.
Example test cases:
[5,4,8,11,null,13,4,7,2,null,null,5,1]1,22,3,4,5,6,77,8,9,1,2,3,4,5,6,7,8888,9,1,2,3,4,5,6,7,8,9[5,4,8,11,null,13,4,7,2,null,null,5,1,4,null,null,3,3,null,null,null,null,2]