Returns the canvas:
generateCanvas(height=40, width=80, background=' ')

No return value:
addRectangle(canvas, left=0, top=0, height=10, width=10, border='*', fill=' ')
addSquare(canvas, left=0, top=0, size=10, border='*', fill=' ')
addPoint(canvas, left=0, top=0, pointChar='*')
addString(canvas, left=0, top=0, message=None)
addCircle(canvas, left=0, top=0, diameter=10, border='*', fill=' ')
showPicture(canvas)
main()