def vertical_gradient(self, x0, y0, x1, y1, start, end):
x0, y0, x1, y1 = self.rect_helper(x0, y0, x1, y1)<EOL>grad = gradient_list(start, end, y1 - y0)<EOL>for x in range(x0, x1 + <NUM_LIT:1>):<EOL><INDENT>for y in range(y0, y1 + <NUM_LIT:1>):<EOL><INDENT>self.point(x, y, grad[y - y0])<EOL><DEDENT><DEDENT>
Draw a vertical gradient