Count to zero then Count up

Question

Since im fairly new to python and programming i have a question of a very basic nature. I want to make a iteration function and a recursive function that does this:

Answer 1

Iterative implementation:

>>> def bounce(num):
...     limit, delta = num + 1, -1
...     while(num != limit):
...         print num
...         num += delta
...         if num == 0:
...             delta = 1

Recursive implementation:

>>> def bounce(num):
...     print num
...     if num: 
...         bounce(num - 1)
...         print num
...         
... 

Output in both the cases:

>>> bounce(4)
4
3
2
1
0
1
2
3
4