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: /// See also:
  ///
  ///  * [Flexible], which does not force the child to fill the available space.
  ///  * [Spacer], a widget that takes up space proportional to it's flex value.
  ///  * The [catalog of layout widgets](https://flutter.dev/widgets/layout/).
  class Expanded extends Flexible {
    /// Creates a widget that expands a child of a [Row], [Column], or [Flex]
  
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.
  