def check_option(opt)
      raise Error, "The option is not an OptBase, #{opt.class} supplied" unless opt.is_a?(OptBase)
      raise Error, "The option #{opt.to_sym} is already used !" if @symbols_used.include?(opt.to_sym)
    end
def check_option(opt)
      raise Error, "The option is not an OptBase, #{opt.class} supplied" unless opt.is_a?(OptBase)
      raise Error, "The option #{opt.to_sym} is already used !" if @symbols_used.include?(opt.to_sym)
    end
Ensures the opt given is valid

 @param [ OptBase ] opt

 @return [ void ]