anchor.diff:  ///  * [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 it's flex value.
  +///  * [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.
  
positive.code: ///  * [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.
  ///    that may be sized smaller (leaving some remaining room unused).
  ///  * The [catalog of layout widgets](https://flutter.dev/widgets/layout/).
  class Flex extends MultiChildRenderObjectWidget {
  
negative.code: ///    that may size smaller (leaving some remaining room unused).
  ///  * [SingleChildScrollView], whose documentation discusses some ways to
  ///    use a [Column] inside a scrolling container.
  ///  * [Spacer], a widget that takes up space proportional to its flex value.
  ///  * The [catalog of layout widgets](https://flutter.dev/widgets/layout/).
  class Column extends Flex {
    /// Creates a vertical array of children.
  