Question 332041
Simply graph the horizontal line at y=4 (green line) and a vertical line at x=0 (ie over the y axis) (blue line)


{{{ drawing(500, 500, -10, 10, -10, 10,
 graph( 500, 500, -10, 10, -10, 10,0,4),
 blue(line(0,-20,0,20))
)}}}