blank space + input()

[ichabod801]

What alternative would you recommend?

You can use isdigit(), but that will be False for '-1', which will convert to an integer. If you only want positive numbers, that's not a problem. If you want to include negatives, the conditional becomes a little messy: if text.isdigit() or (text[0] == '-' and text[1:].isdigit()):. At that point I would just go with try except:

try:
    print(int(x) + 2)
except ValueError:
    if x.lower() == 'quit':
        break
    else:
        print('Integers only, please.')