<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def stereonet2xyz(lon, lat):
 """ 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. """

    lon, lat = np.atleast_1d(lon, lat)
    x, y, z = sph2cart(lon, lat)
    return y, z, -x