anchor.diff:  }
   
   /// A material widget displayed at the bottom of an app for selecting among a
  -/// small number of views.
  +/// small number of views, typically between three and five.
   ///
   /// The bottom navigation bar consists of multiple items in the form of
   /// text labels, icons, or both, laid out on top of a piece of material. It
  
positive.code:   /// The color of the selected item when bottom navigation bar is
    /// [BottomNavigationBarType.fixed].
    ///
    /// If [fixedColor] is null, it will use the theme's primary color. The [fixedColor]
    /// field will be ignored if the [type] is not [BottomNavigationBarType.fixed].
    final Color fixedColor;
  
    /// The size of all of the [BottomNavigationBarItem] icons.
  
negative.code:   /// Creates a bottom navigation bar, typically used in a [Scaffold] where it
    /// is provided as the [Scaffold.bottomNavigationBar] argument.
    ///
    /// The length of [items] must be at least two.
    ///
    /// If [type] is null then [BottomNavigationBarType.fixed] is used when there
    /// are two or three [items], [BottomNavigationBarType.shifting] otherwise.
    ///
    /// If [fixedColor] is null then the theme's primary color,
    /// [ThemeData.primaryColor], is used. However if [BottomNavigationBar.type] is
    /// [BottomNavigationBarType.shifting] then [fixedColor] is ignored.
    BottomNavigationBar({
      Key key,
      @required this.items,
  