def add_style(cell_ref, *styles)
      item = self[cell_ref]
      cells = item.is_a?(Array) ? item : [item]
      cells.each do |cell|
        styles.each do |style|
          cell.add_style(style)
        end
      end
    end
def add_style(cell_ref, *styles)
      item = self[cell_ref]
      cells = item.is_a?(Array) ? item : [item]
      cells.each do |cell|
        styles.each do |style|
          cell.add_style(style)
        end
      end
    end
Example to add a single style:
   add_style 'A1:B5', b: true, sz: 14

 Example to add multiple styles:
   bold = { b: true }
   large_text = { sz: 30 }
   add_style 'B2:F8', bold, large_text