DDA Line Drawing Algorithms Line Coordinates

def ROUND(a):
  return int(a + 0.5)
def drawDDA(x1,y1,x2,y2):
  x,y = x1,y1
  length = (x2-x1) if (x2-x1) > (y2-y1) else (y2-y1)
  dx = (x2-x1)/float(length)
  dy = (y2-y1)/float(length)
  print ('x = %s, y = %s' % (((ROUND(x),ROUND(y)))))
  for i in range(length):
    x += dx
    y += dy
    print ('x = %s, y = %s' % (((ROUND(x),ROUND(y)))))
drawDDA(2,5,10,20)