anchor.diff:  /// such as <https://wakamaifondue.com/> to examine your fonts to
   /// determine what features are available.
   ///
  -/// {@tool sample --template=freeform}
  +/// {@tool sample --template=stateless_widget_material}
   ///
   /// This example shows usage of several OpenType font features,
   /// including Small Caps (selected manually using the "smcp" code),
   /// old-style figures, fractional ligatures, and stylistic sets.
   ///
  +/// ```dart dartImports
  +/// import 'dart:ui';
  +/// ```
  +///
  +/// ```dart preamble
  +/// final TextStyle titleStyle = TextStyle(
  +///   fontSize: 18,
  +///   fontFeatures: const <FontFeature>[FontFeature.enable('smcp')],
  +///   color: Colors.blueGrey[600],
  +/// );
  +/// ```
  +///
   /// ```dart
  -/// class TypePage extends StatelessWidget {
  +/// Widget build(BuildContext context) {
   ///   // The Cardo, Milonga and Raleway Dots fonts can be downloaded from
   ///   // Google Fonts (https://www.google.com/fonts).
  -///
  -///   final titleStyle = TextStyle(
  -///     fontSize: 18,
  -///     fontFeatures: [FontFeature.enable('smcp')],
  -///     color: Colors.blueGrey[600],
  -///   );
  -///
  -///   @override
  -///   Widget build(BuildContext context) {
  -///     return Scaffold(
  -///       body: Center(
  -///         child: Column(
  -///           mainAxisAlignment: MainAxisAlignment.center,
  -///           children: <Widget>[
  -///             Spacer(flex: 5),
  -///             Text('regular numbers have their place:', style: titleStyle),
  -///             Text('The 1972 cup final was a 1-1 draw.',
  -///                 style: TextStyle(
  +///   return Scaffold(
  +///     body: Center(
  +///       child: Column(
  +///         mainAxisAlignment: MainAxisAlignment.center,
  +///         children: <Widget>[
  +///           const Spacer(flex: 5),
  +///           Text('regular numbers have their place:', style: titleStyle),
  +///           const Text('The 1972 cup final was a 1-1 draw.',
  +///               style: TextStyle(
  +///                 fontFamily: 'Cardo',
  +///                 fontSize: 24,
  +///               )),
  +///           const Spacer(),
  +///           Text('but old-style figures blend well with lower case:',
  +///               style: titleStyle),
  +///           const Text('The 1972 cup final was a 1-1 draw.',
  +///               style: TextStyle(
   ///                   fontFamily: 'Cardo',
   ///                   fontSize: 24,
  -///                 )),
  -///             Spacer(),
  -///             Text('but old-style figures blend well with lower case:',
  -///                 style: titleStyle),
  -///             Text('The 1972 cup final was a 1-1 draw.',
  -///                 style: TextStyle(
  -///                     fontFamily: 'Cardo',
  -///                     fontSize: 24,
  -///                     fontFeatures: [FontFeature.oldstyleFigures()])),
  -///             Spacer(),
  -///             Divider(),
  -///             Spacer(),
  -///             Text('fractions look better with a custom ligature:',
  -///                 style: titleStyle),
  -///             Text('Add 1/2 tsp of flour and stir.',
  -///                 style: TextStyle(
  -///                     fontFamily: 'Milonga',
  -///                     fontSize: 24,
  -///                     fontFeatures: [FontFeature.alternativeFractions()])),
  -///             Spacer(),
  -///             Divider(),
  -///             Spacer(),
  -///             Text('multiple stylistic sets in one font:', style: titleStyle),
  -///             Text('Raleway Dots',
  -///                 style: TextStyle(fontFamily: 'Raleway Dots', fontSize: 48)),
  -///             Text('Raleway Dots',
  -///                 style: TextStyle(
  -///                   fontFeatures: [FontFeature.stylisticSet(1)],
  -///                   fontFamily: 'Raleway Dots',
  -///                   fontSize: 48,
  -///                 )),
  -///             Spacer(flex: 5),
  -///           ],
  -///         ),
  +///                   fontFeatures: const <FontFeature>[FontFeature.oldstyleFigures()])),
  +///           const Spacer(),
  +///           const Divider(),
  +///           const Spacer(),
  +///           Text('fractions look better with a custom ligature:',
  +///               style: titleStyle),
  +///           const Text('Add 1/2 tsp of flour and stir.',
  +///               style: TextStyle(
  +///                   fontFamily: 'Milonga',
  +///                   fontSize: 24,
  +///                   fontFeatures: <FontFeature>[FontFeature.alternativeFractions()])),
  +///           const Spacer(),
  +///           const Divider(),
  +///           const Spacer(),
  +///           Text('multiple stylistic sets in one font:', style: titleStyle),
  +///           const Text('Raleway Dots',
  +///               style: TextStyle(fontFamily: 'Raleway Dots', fontSize: 48)),
  +///           Text('Raleway Dots',
  +///               style: TextStyle(
  +///                 fontFeatures: <FontFeature>[FontFeature.stylisticSet(1)],
  +///                 fontFamily: 'Raleway Dots',
  +///                 fontSize: 48,
  +///               )),
  +///           const Spacer(flex: 5),
  +///         ],
   ///       ),
  -///     );
  -///   }
  +///     ),
  +///   );
   /// }
   /// ```
   /// {@end-tool}
  
positive.code:   ///
    /// This may override other features that substitute glyphs.
    ///
    /// {@tool sample --template=freeform}
    ///
    /// The Piazzolla font supports the `ordn` feature. It causes
    /// alphabetic glyphs to become smaller and superscripted.
    ///
    /// ```dart
    /// class Demo extends StatelessWidget {
    ///   // The Piazzolla font can be downloaded from Google Fonts (https://www.google.com/fonts).
    ///   @override
    ///   Widget build(BuildContext context) {
    ///     return Text(
    ///       '1st, 2nd, 3rd, 4th...',
    ///       style: TextStyle(
    ///         fontFamily: 'Piazzolla',
    ///         fontFeatures: <FontFeature>[
    ///           FontFeature.ordinalForms(),
    ///         ],
    ///       ),
    ///     );
    ///   }
    /// }
    /// ```
    ///
  
negative.code:   /// angled), and the "0" rendering changes from a center dot to a
    /// slash.
    ///
    /// ```dart dartImports
    /// import 'dart:ui';
    /// ```
    ///
    /// ```dart
    /// Widget build(BuildContext context) {
    ///   // The Source Code Pro font can be downloaded from Google Fonts (https://www.google.com/fonts).
    ///   return const Text(
    ///     r'Agile Game - $100 initial bet',
    ///     style: TextStyle(
    ///       fontFamily: 'Source Code Pro',
    ///       fontFeatures: <FontFeature>[
    ///         FontFeature.stylisticAlternates(),
    ///       ],
    ///     ),
    ///   );
    /// }
    /// ```
    ///
  