<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def rav2xf(rot, av):
 """ This routine determines a state transformation matrix from a rotation matrix and the angular velocity of the rotation. http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/rav2xf_c.html :param rot: Rotation matrix. :type rot: 3x3-Element Array of floats :param av: Angular velocity vector. :type av: 3-Element Array of floats :return: State transformation associated with rot and av. :rtype: 6x6-Element Array of floats """

    rot = stypes.toDoubleMatrix(rot)
    av = stypes.toDoubleVector(av)
    xform = stypes.emptyDoubleMatrix(x=6, y=6)
    libspice.rav2xf_c(rot, av, xform)
    return stypes.cMatrixToNumpy(xform)