// The flag of France is three vertical stripes of equal width.
// Blue stripe runs from the left edge to 1/3 of the screen.
// White stripe runs from 1/3 of the screen to 2/3 of the screen.
// Red stripe runs from 2/3 of the screen to the end of the screen.
fill_rectangle(0, 0, (1/3)*width, height, 'blue')
fill_rectangle((1/3)*width, 0, (2/3)*width, height, 'white')
fill_rectangle((2/3)*width, 0, width, height, 'red')