code: @Nonnull
    public ESuccess writeTo (@Nonnull final IWritableResource aRes)
    {
      return writeTo (aRes.getOutputStream (EAppend.TRUNCATE));
    }
docs: Write the current workbook to a writable resource.
  
  @param aRes
  The resource to write to. May not be <code>null</code>.
  @return {@link ESuccess}