_layout_for_option

# File actionpack/lib/abstract_controller/layouts.rb, line 324
    def _layout_for_option(name)
      case name
      when String     then name
      when true       then _default_layout(true)
      when :default   then _default_layout(false)
      when false, nil then nil
      else
        raise ArgumentError,
          "String, true, or false, expected for `layout'; you passed #{name.inspect}"
      end
    end