anchor.diff:      TextStyle? caption,
       TextStyle? button,
       TextStyle? overline,
  -    @Deprecated(
  -      'This is the term used in the 2014 version of material design. The modern term is headline1. '
  -      'This feature was deprecated after v1.13.8.',
  -    )
  -    TextStyle? display4,
  -    @Deprecated(
  -      'This is the term used in the 2014 version of material design. The modern term is headline2. '
  -      'This feature was deprecated after v1.13.8.',
  -    )
  -    TextStyle? display3,
  -    @Deprecated(
  -      'This is the term used in the 2014 version of material design. The modern term is headline3. '
  -      'This feature was deprecated after v1.13.8.',
  -    )
  -    TextStyle? display2,
  -    @Deprecated(
  -      'This is the term used in the 2014 version of material design. The modern term is headline4. '
  -      'This feature was deprecated after v1.13.8.',
  -    )
  -    TextStyle? display1,
  -    @Deprecated(
  -      'This is the term used in the 2014 version of material design. The modern term is headline5. '
  -      'This feature was deprecated after v1.13.8.',
  -    )
  -    TextStyle? headline,
  -    @Deprecated(
  -      'This is the term used in the 2014 version of material design. The modern term is headline6. '
  -      'This feature was deprecated after v1.13.8.',
  -    )
  -    TextStyle? title,
  -    @Deprecated(
  -      'This is the term used in the 2014 version of material design. The modern term is subtitle1. '
  -      'This feature was deprecated after v1.13.8.',
  -    )
  -    TextStyle? subhead,
  -    @Deprecated(
  -      'This is the term used in the 2014 version of material design. The modern term is subtitle2. '
  -      'This feature was deprecated after v1.13.8.',
  -    )
  -    TextStyle? subtitle,
  -    @Deprecated(
  -      'This is the term used in the 2014 version of material design. The modern term is bodyText1. '
  -      'This feature was deprecated after v1.13.8.',
  -    )
  -    TextStyle? body2,
  -    @Deprecated(
  -      'This is the term used in the 2014 version of material design. The modern term is bodyText2. '
  -      'This feature was deprecated after v1.13.8.',
  -    )
  -    TextStyle? body1,
     }) {
  -    assert(
  -      (headline1 == null && headline2 == null && headline3 == null && headline4 == null && headline5 == null && headline6 == null &&
  -       subtitle1 == null && subtitle2 == null &&
  -       bodyText1 == null && bodyText2 == null) ||
  -      (display4 == null && display3 == null && display2 == null && display1 == null && headline == null && title == null &&
  -       subhead == null && subtitle == null &&
  -       body2 == null && body1 == null),
  -      'Cannot mix 2014 and 2018 terms in call to TextTheme.copyWith().',
  -    );
       return TextTheme(
  -      headline1: headline1 ?? display4 ?? this.headline1,
  -      headline2: headline2 ?? display3 ?? this.headline2,
  -      headline3: headline3 ?? display2 ?? this.headline3,
  -      headline4: headline4 ?? display1 ?? this.headline4,
  -      headline5: headline5 ?? headline ?? this.headline5,
  -      headline6: headline6 ?? title ?? this.headline6,
  -      subtitle1: subtitle1 ?? subhead ?? this.subtitle1,
  -      subtitle2: subtitle2 ?? subtitle ?? this.subtitle2,
  -      bodyText1: bodyText1 ?? body2 ?? this.bodyText1,
  -      bodyText2: bodyText2 ?? body1 ?? this.bodyText2,
  +      headline1: headline1 ?? this.headline1,
  +      headline2: headline2 ?? this.headline2,
  +      headline3: headline3 ?? this.headline3,
  +      headline4: headline4 ?? this.headline4,
  +      headline5: headline5 ?? this.headline5,
  +      headline6: headline6 ?? this.headline6,
  +      subtitle1: subtitle1 ?? this.subtitle1,
  +      subtitle2: subtitle2 ?? this.subtitle2,
  +      bodyText1: bodyText1 ?? this.bodyText1,
  +      bodyText2: bodyText2 ?? this.bodyText2,
         caption: caption ?? this.caption,
         button: button ?? this.button,
         overline: overline ?? this.overline,
  
positive.code:   /// If you do decide to create your own text theme, consider using one of
    /// those predefined themes as a starting point for [copyWith] or [apply].
    const TextTheme({
      TextStyle? headline1,
      TextStyle? headline2,
      TextStyle? headline3,
      TextStyle? headline4,
      TextStyle? headline5,
      TextStyle? headline6,
      TextStyle? subtitle1,
      TextStyle? subtitle2,
      TextStyle? bodyText1,
      TextStyle? bodyText2,
      this.caption,
      this.button,
      this.overline,
      @Deprecated(
        'This is the term used in the 2014 version of material design. The modern term is headline1. '
        'This feature was deprecated after v1.13.8.',
      )
      TextStyle? display4,
      @Deprecated(
        'This is the term used in the 2014 version of material design. The modern term is headline2. '
        'This feature was deprecated after v1.13.8.',
      )
      TextStyle? display3,
      @Deprecated(
        'This is the term used in the 2014 version of material design. The modern term is headline3. '
        'This feature was deprecated after v1.13.8.',
      )
      TextStyle? display2,
      @Deprecated(
        'This is the term used in the 2014 version of material design. The modern term is headline4. '
        'This feature was deprecated after v1.13.8.',
      )
      TextStyle? display1,
      @Deprecated(
        'This is the term used in the 2014 version of material design. The modern term is headline5. '
        'This feature was deprecated after v1.13.8.',
      )
      TextStyle? headline,
      @Deprecated(
        'This is the term used in the 2014 version of material design. The modern term is headline6. '
        'This feature was deprecated after v1.13.8.',
      )
      TextStyle? title,
      @Deprecated(
        'This is the term used in the 2014 version of material design. The modern term is subtitle1. '
        'This feature was deprecated after v1.13.8.',
      )
      TextStyle? subhead,
      @Deprecated(
        'This is the term used in the 2014 version of material design. The modern term is subtitle2. '
        'This feature was deprecated after v1.13.8.',
      )
      TextStyle? subtitle,
      @Deprecated(
        'This is the term used in the 2014 version of material design. The modern term is bodyText1. '
        'This feature was deprecated after v1.13.8.',
      )
      TextStyle? body2,
      @Deprecated(
        'This is the term used in the 2014 version of material design. The modern term is bodyText2. '
        'This feature was deprecated after v1.13.8.',
      )
      TextStyle? body1,
    }) : assert(
           (headline1 == null && headline2 == null && headline3 == null && headline4 == null && headline5 == null && headline6 == null &&
            subtitle1 == null && subtitle2 == null &&
            bodyText1 == null && bodyText2 == null) ||
           (display4 == null && display3 == null && display2 == null && display1 == null && headline == null && title == null &&
            subhead == null && subtitle == null &&
            body2 == null && body1 == null),
           'Cannot mix 2014 and 2018 terms in call to TextTheme() constructor.',
         ),
         headline1 = headline1 ?? display4,
         headline2 = headline2 ?? display3,
         headline3 = headline3 ?? display2,
         headline4 = headline4 ?? display1,
         headline5 = headline5 ?? headline,
         headline6 = headline6 ?? title,
         subtitle1 = subtitle1 ?? subhead,
         subtitle2 = subtitle2 ?? subtitle,
         bodyText1 = bodyText1 ?? body2,
         bodyText2 = bodyText2 ?? body1;
  
    /// Extremely large text.
    final TextStyle? headline1;
  
negative.code:   ///
    /// Typically used for captions or to introduce a (larger) headline.
    final TextStyle? overline;
  
    /// Creates a copy of this text theme but with the given fields replaced with
    /// the new values.
  