}

  /**
   * Returns a stream consisting of the results of applying the given function to the elements of
   * {@code stream} and their indices in the stream. For example,
   *
   * <pre>{@code
   * mapWithIndex(
   *     Stream.of("a", "b", "c"),
   *     (e, index) -> index + ":" + e)
   * }</pre>
   *
   * <p>would return {@code Stream.of("0:a", "1:b", "2:c")}.
   *
   * <p>The resulting stream is <a

      local col = std.mod(index, panelsPerRow);
      panel + { gridPos+: { x: panel.gridPos.w * col } };

    local panelsBeforeRowsWithX = std.mapWithIndex(CalculateXforPanel, panelsBeforeRows);

    local rowPanelsWithX =
      std.map(
        function(row)
          row + { panels: std.mapWithIndex(CalculateXforPanel, row.panels) },
        rowPanels
      );

  }

  /**
   * Returns a stream consisting of the results of applying the given function to the elements of
   * {@code stream} and their indices in the stream. For example,
   *
   * <pre>{@code
   * mapWithIndex(
   *     Stream.of("a", "b", "c"),
   *     (e, index) -> index + ":" + e)
   * }</pre>
   *
   * <p>would return {@code Stream.of("0:a", "1:b", "2:c")}.
   *
   * <p>The resulting stream is <a