# set an opacity value
opacity(.5)
# set a color and draw some rect and text
fill(1, 0, 0)
rect(10, 10, 600, 600)
fill(0, 1, 0)
rect(390, 390, 600, 600)
fontSize(400)
fill(0, 0, 1)
text("draw", (500, 500), align="center")