human
Solve the following python programming problem given the following code:
def _lift_arg(self, arg, block = None) : 
    unchanged = [True] 
    def _lift(x) : 
        if isinstance (x, ir.Expr) : 
            lifted_arg = self.lift (x, block = block) 
            if (lifted_arg is not x) : 
                unchanged [0] = False 
else : 
            lifted_arg = x 
return lifted_arg 
if (arg is None) : 
        return (arg, True) 
if isinstance (_lift, (tuple, list)) : 
        result = [_lift (x) for x in arg] 
else : 
        result = _lift (arg) 
return (result, unchanged [0]) 

    
    

    Fix the buggy line: if isinstance (_lift, (tuple, list)) :
assistant
#Here is Python code to fix the buggy line: if isinstance (_lift, (tuple, list)) :
.

if isinstance (arg, (tuple, list)) :