collatz.py

def get_number()
  while (!num): # We'll keep trying until num has a value in it
    try:
        num = int(input()) # Prompt for a number
    except ValueError: # If we couldn't make it an int...
        print("enter an integer") # ... complain
  return num

def collatz_next(n):
  # return next number after n in the collatz sequence
  pass


def print_collatz_sequence(n):
  # keep reducing n until you get to 1, printing along the way
  # this will call collatz_next in a loop of some kind
  pass

def main():
  number = get_number()
  print_collatz_sequence(number)