Stroke a line, uses the stroke color set in stroke().
YourScreen.line(x1, y1, x2, y2)
Nothing
YourScreen.beginDraw();
YourScreen.clear();
YourScreen.stroke(0, 0, 255);
YourScreen.line(0, 0, YourScreen.width() - 1, YourScreen.height() - 1);
YourScreen.endDraw();