class Talk
  def initialize(name, &block)
    @name = name
    @slides = []
    slide(name) and instance_eval(&block)
  end

  def slide(name)
    @slides << Slide.new(name)
  end

  def to_html
    @slides.map { |s| s.to_html }.join("\n")
  end
end

def Talk(*args, &block); args.empty? ? Talk : Talk.new(*args, &block) end