class ActionController::MimeResponds::Collector::VariantCollector

def any(*args, &block)
  if block_given?
    if args.any? && args.none?{ |a| a == @variant }
      args.each{ |v| @variants[v] = block }
    else
      @variants[:any] = block
    end
  end
end

def initialize(variant = nil)
  @variant = variant
  @variants = {}
end

def method_missing(name, *args, &block)
  @variants[name] = block if block_given?
end

def variant
  if @variant.nil?
    @variants[:none] || @variants[:any]
  elsif (@variants.keys & @variant).any?
    @variant.each do |v|
      return @variants[v] if @variants.key?(v)
    end
  else
    @variants[:any]
  end
end