code: def qdq2av(q, dq):
      
      q = stypes.toDoubleVector(q)
      dq = stypes.toDoubleVector(dq)
      vout = stypes.emptyDoubleVector(3)
      libspice.qdq2av_c(q, dq, vout)
      return stypes.cVectorToPython(vout)
docs: Derive angular velocity from a unit quaternion and its derivative
      with respect to time.
  
      http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/qdq2av_c.html
  
      :param q: Unit SPICE quaternion.
      :type q: 4-Element Array of floats
      :param dq: Derivative of q with respect to time
      :type dq: 4-Element Array of floats
      :return: Angular velocity defined by q and dq.
      :rtype: 3-Element Array of floats