anchor.diff:  /// Property with a [value] of type [T].
   ///
   /// If the default `value.toString()` does not provide an adequate description
  -/// of the value, specify [description] defining a custom description.
  +/// of the value, specify `description` defining a custom description.
   ///
   /// The [hidden] property specifies whether the property should be hidden from
   /// the default output (e.g. the output given by [toStringDeep]).
  
positive.code:   /// description of a property should also be a single line if possible.
    String toDescription({ TextTreeConfiguration parentConfiguration });
  
    /// Whether to show a separator between [name] and [description].
    ///
    /// If false, name and description should be shown with no separation.
    /// `:` is typically used as a separator when displaying as text.
  
negative.code:   ///
    ///     // Displaying the depth value would be distracting. Instead only display
    ///     // if the depth value is missing.
    ///     properties.add(new ObjectFlagProperty<int>('depth', depth, ifNull: 'no depth'));
    ///
    ///     // bool flag that is only shown when the value is true.
    ///     properties.add(new FlagProperty('using primary controller', value: primary));
    ///
    ///     properties.add(new FlagProperty(
    ///       'isCurrent',
    ///       value: isCurrent,
    ///       ifTrue: 'active',
  