TypeError：“ str”对象不可调用，但是我没有覆盖str方法吗？

我认为这与使用input（）函数有关？ 我阅读了其他暗示它的答案，因为您正在尝试重新定义str，但是您可以看到Im在这里没有这样做。我知道有一种更好的方法可以实现此任务的目标，但我只是用它来探索python而不是寻求最佳。

#Ask the user for a string and print out whether this string is a palindrome or not.
#(A palindrome is a string that reads the same forwards and backwards.)
repeat = True
while repeat == True:
    print(" enter a string " )
    input = str(input())


    #split string into an array of characters
    string = list(input)
    print(string)
    stringReverse = list(input[::-1])
    print(stringReverse)

    #loop an check if the first char matches last char up to the halfway
    length = len(string)
    #get the halfway point
    if length%2 == 0:
        #halfway point is even
        halfway = length/2
    else:
        halfway=(length+1)/2 #we are going to ignore this character



    print(halfway)

    print(stringReverse)
    #loop through each character in string
    currentpost = 0
    palindrome=True

    for index, letter in enumerate(string):
        #print(str(index)+ ' ' + letter)
        #print(stringReverse[index])
        print( letter +stringReverse[index])
        if letter == stringReverse[index]:
              print('match')
        else:
            print('break')
            palindrome = False



    print(palindrome)

    print("continue y/n")
    answer = str(input())
    print(answer)
    if answer =="n":
        repeat = False

错误信息如下

Traceback (most recent call last):
  File "/Users/nigel/Desktop/pythonshit/exercises6.py", line 48, in <module>
    answer = str(input())
TypeError: 'str' object is not callable