def add_range(cells)
     sqref = if cells.is_a?(String)
               cells
             elsif cells.is_a?(SimpleTypedList) || cells.is_a?(Array)
               Axlsx::cell_range(cells, false)
             end
     self << ProtectedRange.new(:sqref => sqref, :name => "Range#{size}")
     last
    end
Adds a protected range
@param [Array|String] cells A string range reference or array of cells that will be protected