class << LotteryDraw
   def play
     final = LotteryTicket.new_random
     winners = {}
     @@tickets.each do |buyer, ticket_list|
       ticket_list.each do |ticket|
         score = ticket.score( final )
         next if score.zero?
         winners[buyer] ||= []
         winners[buyer] << [ ticket, score ]
       end
     end
     @@tickets.clear
     winners
   end
 end