plotLine(x0,y0, x1,y1)
      dx = x1 - x0
      dy = y1 - y0
      D = 2*dy - dx
      y = y0

     for x from x0 to x1
        plot(x,y)
        if D > 0
           y = y + 1
           D = D - 2*dx
        end if
        D = D + 2*dy

P1 = (10, 120) and P2 = (18, 117)

ePlot the following points:
10, 120
11, 120
12, 120
13, 120
14, 120
15, 120
16, 120
17, 120