anchor.diff:    /// number of children because the builder is called only for those children
     /// that are actually visible.
     ///
  -  /// Providing a non-null [itemCount] improves the ability of the [ListView] to
  +  /// Providing a non-null `itemCount` improves the ability of the [ListView] to
     /// estimate the maximum scroll extent.
     ///
  -  /// [itemBuilder] will be called only with indices greater than or equal to
  -  /// zero and less than [itemCount].
  +  /// The `itemBuilder` callback will be called only with indices greater than
  +  /// or equal to zero and less than `itemCount`.
  +  ///
  +  /// The `itemBuilder` should actually create the widget instances when called.
  +  /// Avoid using a builder that returns a previously-constructed widget; if the
  +  /// list view's children are created in advance, or all at once when the
  +  /// [ListView] itself is created, it is more efficient to use [new ListView].
  +  /// Even more efficient, however, is to create the instances on demand using
  +  /// this constructor's `itemBuilder` callback.
     ListView.builder({
       Key key,
       Axis scrollDirection: Axis.vertical,
  
positive.code:   /// children because constructing the [List] requires doing work for every
    /// child that could possibly be displayed in the list view instead of just
    /// those children that are actually visible.
    ListView({
      Key key,
      Axis scrollDirection: Axis.vertical,
  
negative.code:   /// number of children because the builder is called only for those children
    /// that are actually visible.
    ///
    /// Providing a non-null `itemCount` improves the ability of the [GridView] to
    /// estimate the maximum scroll extent.
    ///
    /// `itemBuilder` will be called only with indices greater than or equal to
    /// zero and less than `itemCount`.
    ///
    /// The [gridDelegate] argument must not be null.
    GridView.builder({
  