anchor.diff:        TextStyle.lerp(begin.button, end.button, t)
       );
     }
  -
   }
   
  +/// The two material design text themes.
  +///
  +/// [Typography.black] and [Typography.white] define the two text themes used in
  +/// material design. The black text theme, which uses darkly colored glyphs, is
  +/// used on lightly colored backgrounds in light themes. The white text theme,
  +/// which uses lightly colored glyphs, is used on darkly colored backgrounds in
  +/// in light themes and in dark themes.
  +///
  +/// To obtain the current text theme, call [Theme.of] with the current
  +/// [BuildContext] and read the [ThemeData.textTheme] property.
  +///
  +/// See also:
  +///
  +///  * [Theme]
  +///  * [ThemeData]
  +///  * <http://www.google.com/design/spec/style/typography.html>
   class Typography {
     Typography._();
  +
  +  /// A material design text theme with darkly colored glyphs.
     static const TextTheme black = const TextTheme._black();
  +
  +  /// A material design text theme with lightly colored glyphs.
     static const TextTheme white = const TextTheme._white();
   }
  
positive.code:       caption  = const TextStyle(inherit: false, fontSize:  12.0, fontWeight: FontWeight.w400, color: Colors.white70, textBaseline: TextBaseline.alphabetic),
        button   = const TextStyle(inherit: false, fontSize:  14.0, fontWeight: FontWeight.w500, color: Colors.white,   textBaseline: TextBaseline.alphabetic);
  
    final TextStyle display4;
    final TextStyle display3;
    final TextStyle display2;
    final TextStyle display1;
    final TextStyle headline;
    final TextStyle title;
    final TextStyle subhead;
    final TextStyle body2;
    final TextStyle body1;
    final TextStyle caption;
    final TextStyle button;
  
    static TextTheme lerp(TextTheme begin, TextTheme end, double t) {
      return new TextTheme._(
        TextStyle.lerp(begin.display4, end.display4, t),
  
negative.code: // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  
  import 'package:flutter/painting.dart';
  
  import 'colors.dart';
  
  // TODO(eseidel): Font weights are supposed to be language relative.
  // TODO(jackson): Baseline should be language relative.
  // These values are for English-like text.
  // TODO(ianh): There's no font-family specified here.
  
  /// Material design text theme.
  ///
  /// Definitions for the various typographical styles found in material design
  /// (e.g., headline, caption). Rather than creating a [TextTheme] directly,
  /// you can obtain an instance as [Typography.black] or [Typography.white].
  ///
  /// To obtain the current text theme, call [Theme.of] with the current
  /// [BuildContext] and read the [ThemeData.textTheme] property.
  ///
  /// See also:
  ///
  ///  * [Typography]
  ///  * [Theme]
  ///  * [ThemeData]
  ///  * <http://www.google.com/design/spec/style/typography.html>
  class TextTheme {
  
    const TextTheme._(this.display4, this.display3, this.display2, this.display1, this.headline, this.title, this.subhead, this.body2, this.body1, this.caption, this.button);
  