human
Solve the following python programming problem given the following code:
def groupBy(self, val) : 
    "
        Groups the object's values by a criterion. Pass either a string
        attribute to group by, or a function that returns the criterion.
        " 
    def by(result, key, value) : 
        if (key not in result) : 
            result [key] = [] 
result [key].append (value) 
res = self._group (self.obj, val, by) 
    return self._wrap (self) 

    
    

    Fix the buggy line: return self._wrap (self)
assistant
#Here is Python program to fix the buggy line: return self.

return self._wrap (res)