anchor.diff:  ///    compact form.
   ///  * <https://material.google.com/components/chips.html>
   abstract class DeletableChipAttributes {
  +  // This class is intended to be used as an interface, and should not be
  +  // extended directly.
  +  factory DeletableChipAttributes._() => null;
  +
     /// The icon displayed when [onDeleted] is set.
     ///
     /// Defaults to an [Icon] widget set to use [Icons.cancel].
  
positive.code: ///    vertical runs.
  ///  * <https://material.google.com/components/chips.html>
  class ActionChip extends StatelessWidget implements ChipAttributes, TappableChipAttributes {
    const ActionChip({
      Key key,
      this.avatar,
  
negative.code: ///  * [FilterChip], uses tags or descriptive words as a way to filter content.
  ///  * <https://material.google.com/components/chips.html>
  abstract class SelectableChipAttributes {
    // This class is intended to be used as an interface, and should not be
    // extended directly.
    factory SelectableChipAttributes._() => null;
  
    /// Whether or not this chip is selected.
    ///
    /// If [onSelected] is not null, this value will be used to determine if the
  