How to use 'time function' to control the balls appear separately?

[znchb]

# I want to show balls on the screen one by one, not all the balls appear immediately.
# could you please help me to use the time function to control it. Appreciate.

import viz
viz.go()

OriginalBall = viz.add('ball.wrl')

for x in [0, 0.2, 0.4, 0.6, 0.8]: ## nested loop
for y in [0, 0.3, 0.6, 0.9]:
ball = OriginalBall.copy() ##use the copy() to save cpu resource
ball.translate(2+x, 2+y, 2)
ball.setScale(0.02,0.02,0.02)