Module.class.class_exec {
  def async(*method_names)
    method_names.each do |method_name|
      original_method = instance_method(method_name)
      define_method(method_name) do |*args,&blk|
        work = Work.new { original_method.bind(self).call(*args,&blk) }  #<--- what does this bind method do?
        Async.instance.run { work.calc }
        return work
      end
    end
  end
}