Complete the implementation of the findNode method below.

Purpose: Search the given subtree, rooted at parameter subRoot, for a node containing the element e$.$

Return: If e is found, return reference to the TreeNode object containing e$.$ If e is not found, return null.

Note: You may use recursion or iteration as per your preference. You may assume that e is not null.

private TreeNode findNode$($E e$,$ TreeNode subRoot$)\{$

$//$ your code goes here

$\}$