public ITracksSearcher CreatedAt(DateTimeOffset? @from = null, DateTimeOffset? to = null) { return Range("created_at", @from.ToParameterValue(x => x.UtcDateTime.ToString(dateFormat, CultureInfo.InvariantCulture)), to.ToParameterValue(x => x.UtcDateTime.ToString(dateFormat, CultureInfo.InvariantCulture))); }