code: def oscltx(state, et, mu):
      
      state = stypes.toDoubleVector(state)
      et = ctypes.c_double(et)
      mu = ctypes.c_double(mu)
      elts = stypes.emptyDoubleVector(20)
      libspice.oscltx_c(state, et, mu, elts)
      return stypes.cVectorToPython(elts)[0:11]
docs: Determine the set of osculating conic orbital elements that 
      corresponds to the state (position, velocity) of a body at some 
      epoch. In additional to the classical elements, return the true 
      anomaly, semi-major axis, and period, if applicable. 
      
      https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/oscltx_c.html
      
      :param state: State of body at epoch of elements. 
      :type state: 6-Element Array of floats
      :param et: Epoch of elements. 
      :type et: float
      :param mu: Gravitational parameter (GM) of primary body. 
      :type mu: float
      :return: Extended set of classical conic elements.