dim as double i,a,b,pi

pi = 3.1459
c = 2
a = pi
b = 3 * pi / 2
do
for i = 0 to 1 step .005
CIRCLE (320, 100), 70 , c, , , i
CIRCLE (320, 100), 50 , 15, a, b, i
_delay 0.00125
cls
next
for i = 1 to 0 step -.005
CIRCLE (320, 100), 70 , c, , , i
CIRCLE (320, 100), 50 , 15, a, b, i
_delay 0.00125
cls
next
if c = 2 then
  c = 12: a = pi/2 : b = pi
else
  c = 2 : a = pi : b = 3 * pi / 2
end if
loop