In the following code, a.visible = False affects b:
#!/usr/bin/python
from __future__ import print_function, division
from visual import *
import time
a = sphere( pos=(-1,0,0) )
b = sphere( pos=(1,0,0) )
time.sleep( 1 )
a.opacity = .75
time.sleep( 1 )
a.opacity = 1
time.sleep( 1 )
a.visible = False
time.sleep( 1 )
a.color = color.red