code: def split(line, lines):
      
      out = empty((len(lines) + 1, 4))
  
      p1 = line[:2]
      for n, l2 in enumerate(lines):
          p2 = intersection(line, l2)
          out[n][:2] = p1
          out[n][2:] = p2
          p1 = p2
      out[n + 1][:2] = p2
      out[n + 1][2:] = line[2:]
      return out
docs: split <line> into multiple sublines
      using intersection with <lines>