A example for try to fixing user input from Python script

gistfile1.py

# -*- coding: utf8 -*-

print "Insisting on fixing user input"

first = 1
second = 2
third = 3
while 1:
    try:
        extra = input("What is the extra value? ")
        break
    except StandardError:
        print "That's not a number. Please try again."

total = first+second+third+extra
print total