anchor.diff:    /// Returns a string with hours, minutes, seconds, and microseconds, in the
     /// following format: `H:MM:SS.mmmmmm`. For example,
     /// ```dart
  -  /// var d = Duration(days: 1, hours: 1, minutes: 33, microseconds: 500);
  -  /// d.toString();  // "25:33:00.000500"
  -  ///
  -  /// d = Duration(days: 0, hours: 1, minutes: 10, microseconds: 500);
  -  /// d.toString();  // "1:10:00.000500"
  +  /// var d = const Duration(days: 1, hours: 1, minutes: 33, microseconds: 500);
  +  /// print(d.toString()); // 25:33:00.000500
  +  ///
  +  /// d = const Duration(hours: 1, minutes: 10, microseconds: 500);
  +  /// print(d.toString()); // 1:10:00.000500
     /// ```
     String toString() {
       var microseconds = inMicroseconds;
  
positive.code:   /// and it might lose precision.
    ///
    /// All arguments are 0 by default.
    const Duration(
        {int days = 0,
        int hours = 0,
  
negative.code: ///
  /// Durations are context independent. For example, a duration of 2 days is
  /// always 48 hours, even when it is added to a `DateTime` just when the
  /// time zone is about to make a daylight-savings switch. (See [DateTime.add]).
  ///
  /// Despite the same name, a `Duration` object does not implement "Durations"
  /// as specified by ISO 8601. In particular, a duration object does not keep
  