anchor.diff:    /// selected date time.
     final DateTime initialDateTime;
   
  -  /// Minimum date that the picker can be scrolled to in [CupertinoDatePickerMode.date]
  -  /// and [CupertinoDatePickerMode.dateAndTime] mode. Null if there's no limit.
  +  /// The minimum selectable date that the picker can settle on.
  +  ///
  +  /// When non-null, the user can still scroll the picker to [DateTime]s earlier
  +  /// than [minimumDate], but the [onDateChangeCallback] will not be called on
  +  /// these [DateTime]s. Once let go, the picker will scroll back to [minimumDate].
  +  ///
  +  /// In [CupertinoDatePickerMode.time] mode, a time becomes unselectable if the
  +  /// [DateTime] produced by combining that particular time and the date part of
  +  /// [initialDateTime] is earlier than [minimumDate]. So typically [minimumDate]
  +  /// needs to be set to a [DateTime] that is on the same date as [initialDateTime].
  +  ///
  +  /// Defaults to null. When set to null, the picker does not impose a limit on
  +  /// the earliest [DateTime] the user can select.
     final DateTime minimumDate;
   
  -  /// Maximum date that the picker can be scrolled to in [CupertinoDatePickerMode.date]
  -  /// and [CupertinoDatePickerMode.dateAndTime] mode. Null if there's no limit.
  +  /// The maximum selectable date that the picker can settle on.
  +  ///
  +  /// When non-null, the user can still scroll the picker to [DateTime]s later
  +  /// than [maximumDate], but the [onDateChangeCallback] will not be called on
  +  /// these [DateTime]s. Once let go, the picker will scroll back to [maximumDate].
  +  ///
  +  /// In [CupertinoDatePickerMode.time] mode, a time becomes unselectable if the
  +  /// [DateTime] produced by combining that particular time and the date part of
  +  /// [initialDateTime] is later than [maximumDate]. So typically [maximumDate]
  +  /// needs to be set to a [DateTime] that is on the same date as [initialDateTime].
  +  ///
  +  /// Defaults to null. When set to null, the picker does not impose a limit on
  +  /// the latest [DateTime] the user can select.
     final DateTime maximumDate;
   
     /// Minimum year that the picker can be scrolled to in
  
positive.code:   /// the intervals set in [minimumDate], [maximumDate], [minimumYear], and
    /// [maximumYear].
    ///
    /// [minimumDate] is the minimum [DateTime] that the picker can be scrolled to.
    /// Null if there's no limit. In [CupertinoDatePickerMode.time] mode, if the
    /// date part of [initialDateTime] is after that of the [minimumDate], [minimumDate]
    /// has no effect.
    ///
    /// [maximumDate] is the maximum [DateTime] that the picker can be scrolled to.
    /// Null if there's no limit. In [CupertinoDatePickerMode.time] mode, if the
    /// date part of [initialDateTime] is before that of the [maximumDate], [maximumDate]
    /// has no effect.
    ///
    /// [minimumYear] is the minimum year that the picker can be scrolled to in
    /// [CupertinoDatePickerMode.date] mode. Defaults to 1 and must not be null.
  
negative.code:   /// Whether to use 24 hour format. Defaults to false.
    final bool use24hFormat;
  
    /// Callback called when the selected date and/or time changes. If the new
    /// selected [DateTime] is not valid, or is not in the [minimumDate] through
    /// [maximumDate] range, this callback will not be called.
    ///
    /// Must not be null.
    final ValueChanged<DateTime> onDateTimeChanged;
  