Problem $4.$ In a binary tree there is a natural ordering of the nodes on a given level

of the tree, i$.$e$.,$ the left$-$to$-$right order that you get when you draw the tree. Design

an algorithm that given a tree T and a level k$,$ visits the nodes in level k in this

natural order. Your algorithm should perform the whole traversal in O$($n$)$ time.