# Define a procedure, countdown, that takes a
# positive whole number as its input, and prints
# out a countdown from that number to 1,
# followed by Blastoff!

def countdown(n):
    """Pretty cool countdown mechanism for a rocket!"""
    while n > 0:
        print n
        n = n - 1
        if n == 0:
            print 'Blastoff!'
            
