JES evironment Jython

Write a function drawDiagonalLine2(picture, color), which draws a line on the picture from the lower left corner (x, y) = (0, H-1) to the top right corner (x, y) = (W-1, 0), where W, H are the width and height of the picture, respectively. The equation for that line is y = H' - (H'/W')x, where H' = H - 1 and W' = W - 1.