fizzbuzz.py

import sys

n = None

try:
    n = int(sys.argv[1])
except (ValueError, IndexError) as e:
    pass # Ignore error here

if (len(sys.argv) == 1) or (n is None):
    good_to_go = False
    while not good_to_go:
        input = raw_input("Enter a number: ")
        try:
            n = int(input)
        except ValueError:
            print "Invalid input."
            continue

        good_to_go = True

for n in range(1, n+1):
    s = ''
    if n % 3 == 0:
        s += 'Fizz'
    if n % 5 == 0:
        s += 'Buzz'
    if s:
        print s
    else:
        print n