docs: def splitN(line, n):
      """
      split a line n times
      returns n sublines
      """
      x0, y0, x1, y1 = line
  
      out = empty((n, 4), dtype=type(line[0]))
      px, py = x0, y0
      dx = (x1 - x0) / n
      dy = (y1 - y0) / n
  
      for i in range(n):
          o = out[i]
          o[0] = px
          o[1] = py
          px += dx
          py += dy
          o[2] = px
          o[3] = py
      return out