''' Purpose: demonstrate a function side-effect in Python
'''

# when you pass in a list into a function
# you are able to modify the list without returning it!
def f( x ) :
    ''' Does ???
    '''

    n = len( x )

    # replace all elements in the list x to 0
    for i in range( 0, n ) :
        x[ i ] = 0

    return