def write_selection(pane, active_cell, sqref) #:nodoc:
      attributes  = []
      attributes << ['pane', pane]              if pane
      attributes << ['activeCell', active_cell] if active_cell
      attributes << ['sqref', sqref]            if sqref

      @writer.empty_tag('selection', attributes)
    end
def write_selection(pane, active_cell, sqref) #:nodoc:
      attributes  = []
      attributes << ['pane', pane]              if pane
      attributes << ['activeCell', active_cell] if active_cell
      attributes << ['sqref', sqref]            if sqref

      @writer.empty_tag('selection', attributes)
    end
Write the <selection> element.