human
Solve the following python programming problem given the following code:
def animate(dictOfTuples) : 
    '
    opposite of flatten
    ' 
    def tree() : 
        return defaultdict (tree) 
output = defaultdict (output) 

    
    

    Fix the buggy line: output = defaultdict (output)
assistant
#Here is Python code to fix the buggy line: output = defaultdict (output)
.

output = defaultdict (tree)