Simple Calculator for Tehlug

Tehlug-calc.py

def add(x, y):
    
    return x + y

def sub(x, y):
    
    return x - y

def mul(x, y):
    
    return x * y

def div(x, y):
    
    return x / y

def operation(sign):
    
    if sign == '+':
        return add
    elif sign == '-':
        return sub
    elif sign == '*':
        return mul
    elif sign == '/':
        return div
    else:
        return None
    
def calculate(x, func, y):

    try:
        return func(x, y)
    except (NameError, TypeError) :
        return 'func name is Wrong!use add, sub, mul and div'
    except ZeroDivisionError:
        return 'Division By Zero Is Not Allowed!!!'
    except Exception:
        return 'Unknown Error!'

import re

while True:

    user = raw_input()
    match = re.search(r'(\s*\d+\s*)([/+*-])(\s*\d+\s*)' , user)
    if match:
        op = operation(match.group(2))
        if op:
            print calculate(float(match.group(1)), op, float(match.group(3)))
    else:
        print 'Please Enter Correct Input! number1 Operation number2 (Operations + - * / )'