"""Examples of iteration using the while statement"""

def countdown(n) :
    while n > 0 :
        print n
        n = n-1
    print "Blastoff!"

def num_digits(n) :
    """counts the number of digits in a number"""
    count = 0
    while n > 0 :
        count = count + 1
        n = n // 10
    return count

# what does this function do?

def mystery1(n) :

    i = 1
    s = 0
    while (i < n) :
        s += i         # this is the same as s = s + i
        i += + 1       # same as i = i + 1

    return s

# now how about this one:

def mystery2() :

    n = 1
    while (n > 0) :
        print n
        n += 1      # same as n = n + 1