hand.rb

class Hand
  def straight?
    values = @cards.map{|card| card.value}.uniq.sort
    values.unshift 1 if values.include?(14) # ace can be low
    0.upto(values.length - 5) do |i|
      return true if values[i] + 4 == values[i + 4]
    end
    false
  end
end