Tree height

 tree1 = {

    1: [2, 3],

    2: [4, 5],

    3: [6, None],

    4: [None, None],

    5: [None, None],

    6: [None, None]

}

def tree_height(tree,node):

    if node is None:

        return 0

    else:

        left_height = tree_height(tree,tree[node][0])

        right_hight = tree_height(tree,tree[node][1])

        

        return max(left_height, right_hight)+1

print(tree_height(tree1,1))