docs: def equi(map_axis, centerlon, centerlat, radius, color, alpha=1.0):
      """
      This function enables A95 error ellipses to be drawn in cartopy around
      paleomagnetic poles in conjunction with shoot
      (modified from: http://www.geophysique.be/2011/02/20/matplotlib-basemap-tutorial-09-drawing-circles/).
      """
      if not has_cartopy:
          print('-W- cartopy must be installed to run ipmag.equi')
          return
      glon1 = centerlon
      glat1 = centerlat
      X = []
      Y = []
      for azimuth in range(0, 360):
          glon2, glat2, baz = shoot(glon1, glat1, azimuth, radius)
          X.append(glon2)
          Y.append(glat2)
      X.append(X[0])
      Y.append(Y[0])
  
      plt.plot(X[::-1], Y[::-1], color=color,
               transform=ccrs.Geodetic(), alpha=alpha)