
  [;1m-spec erlang:localtime_to_universaltime(Localtime) -> Universaltime[0m
  [;1m                                           when[0m
  [;1m                                               Localtime ::[0m
  [;1m                                                   calendar:datetime(),[0m
  [;1m                                               Universaltime ::[0m
  [;1m                                                   calendar:datetime().[0m

  Converts local date and time to Universal Time Coordinated (UTC),
  if supported by the underlying OS. Otherwise no conversion is done
  and [;;4mLocaltime[0m is returned. Example:

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

  Failure: [;;4mbadarg[0m if [;;4mLocaltime[0m denotes an invalid date and time.

  [;1m-spec erlang:localtime_to_universaltime(Localtime, IsDst) ->[0m
  [;1m                                           Universaltime[0m
  [;1m                                           when[0m
  [;1m                                               Localtime ::[0m
  [;1m                                                   calendar:datetime(),[0m
  [;1m                                               Universaltime ::[0m
  [;1m                                                   calendar:datetime(),[0m
  [;1m                                               IsDst ::[0m
  [;1m                                                   true | false |[0m
  [;1m                                                   undefined.[0m

  Converts local date and time to Universal Time Coordinated (UTC)
  as [;;4merlang:localtime_to_universaltime/1[0m, but the caller decides
  if Daylight Saving Time is active.

  If [;;4mIsDst == true[0m, [;;4mLocaltime[0m is during Daylight Saving Time, if [;;4m[0m
  [;;4mIsDst == false[0m it is not. If [;;4mIsDst == undefined[0m, the underlying
  OS can guess, which is the same as calling [;;4m[0m
  [;;4merlang:localtime_to_universaltime(Localtime)[0m.

  Examples:

    > erlang:localtime_to_universaltime({{1996,11,6},{14,45,17}}, true).
    {{1996,11,6},{12,45,17}}
    > erlang:localtime_to_universaltime({{1996,11,6},{14,45,17}}, false).
    {{1996,11,6},{13,45,17}}
    > erlang:localtime_to_universaltime({{1996,11,6},{14,45,17}}, undefined).
    {{1996,11,6},{13,45,17}}

  Failure: [;;4mbadarg[0m if [;;4mLocaltime[0m denotes an invalid date and time.
