docs: def girdle_error(ax, fit, **kwargs):
      """
      Plot an attitude measurement on an `mplstereonet` axes object.
      """
      vertices = []
      codes = []
      for sheet in ('upper','lower'):
          err = plane_errors(fit.axes, fit.covariance_matrix,
                  sheet=sheet)
          lonlat = N.array(err)
          lonlat *= -1
          n = len(lonlat)
          if sheet == 'lower':
              lonlat = lonlat[::-1]
          vertices += list(lonlat)
          codes.append(Path.MOVETO)
          codes += [Path.LINETO]*(n-1)
  
      plot_patch(ax, vertices, codes, **kwargs)