anchor.diff:  class Chip extends StatelessWidget implements ChipAttributes, DeletableChipAttributes {
     /// Creates a material design chip.
     ///
  -  /// The [label], [deleteIcon] and [border] arguments must not be null.
  +  /// The [label], [deleteIcon], and [border] arguments must not be null.
     const Chip({
       Key key,
       this.avatar,
  
positive.code: ///  * [ActionChip], represents an action related to primary content.
  ///  * <https://material.google.com/components/chips.html>
  abstract class TappableChipAttributes {
    /// Called when the user taps the chip.
    ///
    /// If [onPressed] is set, then this callback will be called when the user
  
negative.code: ///    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].
  