TypeError：“str”对象的描述符“encode”不适用于“tuple”对象

问：

有人可以帮助修复TypeError吗？它在 python 2 中有效，但在 python 3 中无效。

蟒蛇2：

def ExchangeColumns(RECXX_Output,Modified_Recxx_Output,column1,column2,column3,column4,column5,column6):
with open(RECXX_Output) as infile ,open(Modified_Recxx_Output, 'wb') as outfile:
        reader = csv.DictReader(infile)
        append = (column1,column2,column3,column4,column5,column6)
        outfile.write(','.join(append)+'\n')

蟒蛇3：

def ExchangeColumns(RECXX_Output,Modified_Recxx_Output,column1,column2,column3,column4,column5,column6):
    with open(RECXX_Output) as infile ,open(Modified_Recxx_Output, 'wb') as outfile:
        reader = csv.DictReader(infile)
        append = (column1,column2,column3,column4,column5,column6)
        appendb =  str.encode(append)
        outfile.write(b','.join(appendb)+b'\n')
        ##outfile.write(b','.join(append).encode(encoding='utf-8')+b'\n')