如何在python中使用isdigit来识别运算符？

def is_operator(char):
    operators = ['+', '-', '*', '/']
    return char in operators

def identify_operator(string):
    if len(string) == 1 and string.isdigit():
        return "The input is a single digit number."
    elif len(string) == 1 and is_operator(string):
        return "The input is an operator."
    else:
        return "The input is neither a single digit number nor an operator."

input_string = input("Enter a character: ")
result = identify_operator(input_string)
print(result)