code: def dvhat(s1):
      
      assert len(s1) is 6
      s1 = stypes.toDoubleVector(s1)
      sout = stypes.emptyDoubleVector(6)
      libspice.dvhat_c(s1, sout)
      return stypes.cVectorToPython(sout)
docs: Find the unit vector corresponding to a state vector and the
      derivative of the unit vector.
  
      http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/dvhat_c.html
  
      :param s1: State to be normalized.
      :type s1: 6-Element Array of floats
      :return: Unit vector s1 / abs(s1), and its time derivative.
      :rtype: 6-Element Array of floats