class TreeNode:
def __init__(self, val, left=None, right=None):
self.val = val
self.left = left
self.right = right
def find_max(node):
if (node is None): return ""
return max([find_max(node.left), node.val, find_max(node.right)], key=len)
tree = TreeNode("test", TreeNode("asdasjkdnaskdjasd", TreeNode("")), TreeNode("a"))
print find_max(tree)
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