anchor.diff:    /// The default behavior varies from font to font.
     ///
     /// {@tool sample --template=stateless_widget}
  -  ///
     /// The Kufam font supports the `pnum` feature. It causes the digits
     /// to become proportionally-sized, rather than all being the same
     /// width. In this font this is especially noticeable with the digit
  
positive.code:   /// This feature may override other glyph-substitution features.
    ///
    /// {@tool sample --template=stateless_widget}
    ///
    /// The Cardo font supports the `hlig` feature. It has legacy
    /// ligatures for "VI" and "NT", and various ligatures involving the
    /// "long s". In the example below, both historical forms (`hist 1`)
  
negative.code:   /// This feature may override other glyph-substitution features.
    ///
    /// {@tool sample --template=stateless_widget}
    /// The Cardo font supports the `hist` feature specifically for the
    /// letter "s": it changes occurrences of that letter for the glyph
    /// used by U+017F LATIN SMALL LETTER LONG S.
    ///
    /// ![](https://flutter.github.io/assets-for-api-docs/assets/dart-ui/font_feature_historical.png)
    ///
    /// ** See code in examples/api/lib/ui/text/font_feature.font_feature_historical_forms.0.dart **
    /// {@end-tool}
    ///
    /// See also:
  