docs: def pole_error(ax, fit, **kwargs):
      """
      Plot the error to the pole to a plane on a `mplstereonet`
      axis object.
      """
      ell = normal_errors(fit.axes, fit.covariance_matrix)
      lonlat = -N.array(ell)
      n = len(lonlat)
      codes = [Path.MOVETO]
      codes += [Path.LINETO]*(n-1)
      vertices = list(lonlat)
  
      plot_patch(ax, vertices, codes, **kwargs)