<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def pl2nvp(plane):
 """ Return a unit normal vector and point that define a specified plane. http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/pl2nvp_c.html :param plane: A SPICE plane. :type plane: supporttypes.Plane :return: A unit normal vector and point that define plane. :rtype: tuple """

    assert (isinstance(plane, stypes.Plane))
    normal = stypes.emptyDoubleVector(3)
    point = stypes.emptyDoubleVector(3)
    libspice.pl2nvp_c(ctypes.byref(plane), normal, point)
    return stypes.cVectorToPython(normal), stypes.cVectorToPython(point)