
  -spec erlang:localtime_to_universaltime(Localtime) -> Universaltime
                                             when
                                                 Localtime ::
                                                     calendar:datetime(),
                                                 Universaltime ::
                                                     calendar:datetime().

  Converts local date and time to Universal Time Coordinated (UTC),
  if supported by the underlying OS. Otherwise no conversion is done
  and Localtime is returned. Example:

    > erlang:localtime_to_universaltime({{1996,11,6},{14,45,17}}).
    {{1996,11,6},{13,45,17}}

  Failure: badarg if Localtime denotes an invalid date and time.
