anchor.diff:  ///  * [Column], for a version of this widget that is always vertical.
   ///  * [Expanded], to indicate children that should take all the remaining room.
   ///  * [Flexible], to indicate children that should share the remaining room.
  -///  * [Spacer], a widget that takes up space proportional to it's flex value.
  +///  * [Spacer], a widget that takes up space proportional to its flex value.
   ///    that may be sized smaller (leaving some remaining room unused).
   ///  * The [catalog of layout widgets](https://flutter.dev/widgets/layout/).
   class Flex extends MultiChildRenderObjectWidget {
  
positive.code: ///
  /// {@tool dartpad --template=stateless_widget_material}
  /// This example shows how to use an [Expanded] widget in a [Column] so that
  /// it's middle child, a [Container] here, expands to fill the space.
  ///
  /// ![This results in two thin blue boxes with a larger amber box in between.](https://flutter.github.io/assets-for-api-docs/assets/widgets/expanded_column.png)
  ///
  
negative.code: ///  * [Expanded], to indicate children that should take all the remaining room.
  ///  * [Flexible], to indicate children that should share the remaining room but
  ///    that may by sized smaller (leaving some remaining room unused).
  ///  * [Spacer], a widget that takes up space proportional to its flex value.
  ///  * The [catalog of layout widgets](https://flutter.dev/widgets/layout/).
  class Row extends Flex {
    /// Creates a horizontal array of children.
  