inconsistent map() behavior

[GOTO10]

Since you are trying to make a list, use list() to convert your map object into a list:

number_list = list(map(str, range(0, 10)))

However, since your list only includes strings for single digits 0 through 9, entering a float (like 1.0) or any multi-digit number (11) would not produce the error warning. The code below will return an error for anything other than a single letter (upper or lower case is not considered):

while True:
    enter = input("Enter a letter. ")

    if not enter.isalpha() or len(enter)> 1:
        print('Error!')
    else:
        print(enter)