anchor.diff:    /// If the layout algorithm is strictly height-in-width-out, or is
     /// height-in-width-out when the width is unconstrained, then the height
     /// argument is the height to use.
  +  ///
  +  /// The `height` argument will never be negative or null. It may be infinite.
     ///
     /// If this algorithm depends on the intrinsic dimensions of a child, the
     /// intrinsic dimensions of that child should be obtained using the functions
  
positive.code:   /// Do not override this method. Instead, implement [computeMinIntrinsicWidth].
    @mustCallSuper
    double getMinIntrinsicWidth(double height) {
      return _computeIntrinsicDimension(_IntrinsicDimension.minWidth, height, computeMinIntrinsicWidth);
    }
  
  
negative.code:   /// [computeMaxIntrinsicHeight].
    @mustCallSuper
    double getMaxIntrinsicHeight(double width) {
      assert(() {
        if (width == null) {
          throw new FlutterError(
            'The width argument to getMaxIntrinsicHeight was null.\n'
            'The argument to getMaxIntrinsicHeight must not be negative or null. '
            'If you do not have a specific width in mind, then pass double.INFINITY instead.'
          );
        }
        if (width < 0.0) {
          throw new FlutterError(
            'The width argument to getMaxIntrinsicHeight was negative.\n'
            'The argument to getMaxIntrinsicHeight must not be negative or null. '
            'If you perform computations on another width before passing it to '
            'getMaxIntrinsicHeight, consider using math.max() or double.clamp() '
            'to force the value into the valid range.'
          );
        }
        return true;
      });
      return _computeIntrinsicDimension(_IntrinsicDimension.maxHeight, width, computeMaxIntrinsicHeight);
    }
  
  