public static TariffMetroCommandCalculateInterval First(this TariffMetro tariff)
{
TariffMetroCommand cmd = tariff.Commands.FirstOrDefault();
if (cmd == null)
{
return(null);
}
while (cmd.Type == TariffMetroCommandType.Goto)
{
cmd = tariff.Goto(cmd);
}
return((TariffMetroCommandCalculateInterval)cmd);
}