Balance_bst(node) function note working for me, anybody has the same problem?

def balance_bst(node):
return make_balanced_bst(list_all(node))

list_all() only returns usernames strings as a list but make_balanced_bst() requires a list with both username string and node object.

I could write my own function to make them work but I am only here to confirm if the teacher made a mistake writing the function or I am misusing his code?