code: def AddTimeZoneOption(self, argument_group):
      
      # Note the default here is None so we can determine if the time zone
      # option was set.
      argument_group.add_argument(
          '-z', '--zone', '--timezone', dest='timezone', action='store',
          type=str, default=None, help=(
              'explicitly define the timezone. Typically the timezone is '
              'determined automatically where possible otherwise it will '
              'default to UTC. Use "-z list" to see a list of available '
              'timezones.'))
docs: Adds the time zone option to the argument group.
  
      Args:
        argument_group (argparse._ArgumentGroup): argparse argument group.