code: def Arrows(startPoints, endPoints=None, s=None, scale=1, c="r", alpha=1, res=12):
      
      startPoints = np.array(startPoints)
      if endPoints is None:
          strt = startPoints[:,0]
          endPoints = startPoints[:,1]
          startPoints = strt
      
      arr = vtk.vtkArrowSource()
      arr.SetShaftResolution(res)
      arr.SetTipResolution(res)
      if s:
          sz = 0.02 * s
          arr.SetTipRadius(sz*2)
          arr.SetShaftRadius(sz)
          arr.SetTipLength(sz * 10)
      arr.Update()
      pts = Points(startPoints)
      orients = (endPoints - startPoints) * scale
      arrg = Glyph(pts, arr.GetOutput(), 
                   orientationArray=orients, scaleByVectorSize=True, 
                   c=c, alpha=alpha)
      settings.collectable_actors.append(arrg)
      return arrg
docs: Build arrows between two lists of points `startPoints` and `endPoints`.
      `startPoints` can be also passed in the form ``[[point1, point2], ...]``.
      
      Color can be specfied as a colormap which maps the size of the arrows.
  
      :param float s: fix aspect-ratio of the arrow and scale its cross section
      :param float scale: apply a rescaling factor to the length
      :param c: color or array of colors
      :param str cmap: color arrows by size using this color map
      :param float alpha: set transparency
      :param int res: set arrow resolution
  
      .. hint:: |glyphs_arrow| |glyphs_arrow.py|_