prompt_option_tag

# File actionview/lib/action_view/helpers/date_helper.rb, line 1081
        def prompt_option_tag(type, options)
          prompt =              case options
            when Hash
              default_options = { year: false, month: false, day: false, hour: false, minute: false, second: false }
              default_options.merge!(options)[type.to_sym]
            when String
              options
            else
              I18n.translate(:"datetime.prompts.#{type}", locale: @options[:locale])
            end

          prompt ? content_tag("option", prompt, value: "") : ""
        end