human
Solve the following python programming problem given the following code:
@ classmethod 
def _reduce_from_cols(cls, cols) : 
    def _table_key(c) : 
        if (not isinstance (c.table, expression.TableClause)) : 
            return None 
else : 
            return c.table.key 
colkeys = [(_table_key.key, _table_key (c)) for c in cols] 
    return (_SerializableColumnGetterV2, (colkeys,)) 

    
    

    Fix the buggy line: colkeys = [(_table_key.key, _table_key (c)) for c in cols]
assistant
#Here is Python program to fix the buggy line: colkeys = [(_table_key.

colkeys = [(c.key, _table_key (c)) for c in cols]