anchor.diff:    }
   
     /// Creates a grid specification containing a certain number of equally sized tiles.
  +  /// The tileWidth is the sum of the width of the child it will contain and
  +  /// columnSpacing (even if columnCount is 1). Similarly tileHeight is child's height
  +  /// plus rowSpacing. If the tiles are to completely fill the grid, then their size
  +  /// should be based on the grid's padded interior.
     GridSpecification.fromRegularTiles({
       double tileWidth,
       double tileHeight,
  
positive.code:        rowOffsets = _generateRegularOffsets(rowCount, tileHeight) {
      assert(_debugIsMonotonic(columnOffsets));
      assert(_debugIsMonotonic(rowOffsets));
      assert(padding != null && padding.isNonNegative);
    }
  
  
negative.code: 
    bool shouldRelayout(GridDelegateWithInOrderChildPlacement oldDelegate) {
      return columnSpacing != oldDelegate.columnSpacing
          || rowSpacing != oldDelegate.rowSpacing
          || padding != oldDelegate.padding;
    }
  }
  
  