human
Solve the following python programming problem given the following code:
def __call__(self, monomial) : 
    def inv(l) : 
        if iterable (l) : 
            return tuple ((inv (x) for x in l)) 
return (- l) 
return inv (self.O (self)) 

    
    

    Fix the buggy line: return inv (self.O (self))
assistant
#Here is Python code to fix the buggy line: return inv (self.

return inv (self.O (monomial))