code: def stereonet2xyz(lon, lat):
      
      lon, lat = np.atleast_1d(lon, lat)
      x, y, z = sph2cart(lon, lat)
      return y, z, -x
docs: Converts a sequence of longitudes and latitudes from a lower-hemisphere
      stereonet into _world_ x,y,z coordinates.
  
      Parameters
      ----------
      lon, lat : array-likes
          Sequences of longitudes and latitudes (in radians) from a
          lower-hemisphere stereonet
  
      Returns
      -------
      x, y, z : arrays
          The world x,y,z components of the vectors represented by the lon, lat
          coordinates on the stereonet.