<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def latrec(radius, longitude, latitude):
 """ Convert from latitudinal coordinates to rectangular coordinates. http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/latrec_c.html :param radius: Distance of a point from the origin. :type radius: float :param longitude: Longitude of point in radians. :type longitude: float :param latitude: Latitude of point in radians. :type latitude: float :return: Rectangular coordinates of the point. :rtype: 3-Element Array of floats """

    radius = ctypes.c_double(radius)
    longitude = ctypes.c_double(longitude)
    latitude = ctypes.c_double(latitude)
    rectan = stypes.emptyDoubleVector(3)
    libspice.latrec_c(radius, longitude, latitude, rectan)
    return stypes.cVectorToPython(rectan)