DateTimeOffset f(long msVal) {
    TimeZoneInfo EST = TimeZoneInfo.GetSystemTimeZones().Where(x => x.Id == "Eastern Standard Time").SingleOrDefault() ?? TimeZoneInfo.FindSystemTimeZoneById("America/New_York"); 

    var dt = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc).AddSeconds(msVal / 1000);

    return TimeZoneInfo.ConvertTime(dt, EST);
}

DateTimeOffset f(long msVal) {
    TimeZoneInfo EST = TimeZoneInfo.GetSystemTimeZones().Where(x => x.Id == "Eastern Standard Time").SingleOrDefault() ?? TimeZoneInfo.FindSystemTimeZoneById("America/New_York"); 

    var dt = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc).AddSeconds(msVal / 1000);

    return TimeZoneInfo.ConvertTime(dt, EST);
}

DateTimeOffset f(long msVal) {
    TimeZoneInfo EST = TimeZoneInfo.GetSystemTimeZones().Where(x => x.Id == "Eastern Standard Time").SingleOrDefault() ?? TimeZoneInfo.FindSystemTimeZoneById("America/New_York"); 

    var dt = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc).AddSeconds(msVal / 1000);

    return TimeZoneInfo.ConvertTime(dt, EST);
}