--- include?(mod)  ruby 1.7 feature

    self  ⥸塼 mod 򥤥󥯥롼ɤƤ
    ֤ޤ

        Foo = Module.new
        class Bar
          include Foo
        end
        class Baz < Bar
        end

        p Bar.include? Foo #=> true
        p Baz.include? Foo #=> true

