code: def udf(x):
      
      x = ctypes.c_double(x)
      value = ctypes.c_double()
      libspice.udf_c(x, ctypes.byref(value))
      return value.value
docs: No-op routine for with an argument signature matching udfuns.
      Allways returns 0.0 .
  
      https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/udf_c.html
  
      :param x: Double precision value, unused.
      :type x: float
      :return: Double precision value, unused.
      :rtype: float