anchor.diff:    /// This feature selects the given glyph variant for glyphs in the span.
     ///
     /// {@tool sample --template=stateless_widget}
  -  ///
     /// The Raleway font supports several alternate glyphs. The code
     /// below shows how specific glyphs can be selected. With `aalt` set
     /// to zero, the default, the normal glyphs are used. With a
  
positive.code:   /// feature). The default set if none is specified is 1.
    ///
    /// {@tool sample --template=stateless_widget}
    ///
    /// The Gothic A1 font supports several notational variant sets via
    /// the `nalt` feature.
    ///
  
negative.code:   /// This may override other features that substitute glyphs.
    ///
    /// {@tool sample --template=stateless_widget}
    /// The Piazzolla font supports the `subs` feature. It causes
    /// digits to be smaller and subscripted.
    ///
    /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/font_feature_subs.png)
    ///
    /// ** See code in examples/api/lib/ui/text/font_feature.font_feature_subscripts.0.dart **
    /// {@end-tool}
    ///
    /// See also:
  