判断一个字符串是否是回文_Python

def isPalindrome(sentence):
    str_x = str(sentence)
    str_y = ""
    for i in str_x:
        str_y = i + str_y
    if(str_y == str_x):
        print("是回文")
    else:
        print("不是回文")

isPalindrome("121")

有错误请指正