anchor.diff:  /// and the corresponding size factor is null then the widget will match its
   /// child's size in that dimension. If a size factor is non-null then the
   /// corresponding dimension of this widget will be the product of the child's
  -/// dimension and the size factor. For example if widthFactor is 0.5 then
  -/// the width of this widget will always be half of the child's width.
  +/// dimension and the size factor. For example if widthFactor is 2.0 then
  +/// the width of this widget will always be twice its child's width.
   ///
   /// See also:
   ///
   ///  * [CustomSingleChildLayout]
   ///  * [Center] (which is the same as [Align] but with the [alignment] always
   ///    set to [FractionalOffset.center])
  -///  * [FractionallySizedBox] which sizes its child based on its own size.
  +///  * [FractionallySizedBox] (which sizes its child based on a fraction of its own
  +///    size and positions the child according to a [FractionalOffset] value)
   class Align extends SingleChildRenderObjectWidget {
     /// Creates an alignment widget.
     ///
  
positive.code: /// See also:
  ///
  ///  * [SingleChildLayoutDelegate]
  ///  * [Align] (which positions a single child according to a [FractionalOffset])
  ///  * [CustomMultiChildLayout] (which uses a delegate to position multiple
  ///    children)
  class CustomSingleChildLayout extends SingleChildRenderObjectWidget {
  
negative.code: }
  
  /// Metadata for identifying children in a [CustomMultiChildLayout].
  /// The [MultiChildLayoutDelegate] hasChild, layoutChild, and positionChild
  /// methods use these identifiers.
  class LayoutId extends ParentDataWidget<CustomMultiChildLayout> {
    /// Marks a child with a layout identifier.
    ///
  