For [Design Patterns in Life and Ruby](https://medium.com/series/design-patterns-in-life-and-ruby-fcde31ba51a0/edit)

concrete_strategy.rb

class GrilledChicken
  def cook
    stuffing = []
    stuffing << 'sliced tomato'
    stuffing << 'lettuce'
    stuffing << 'grilled chicken'
    stuffing
  end
end

class BeefPatty
  def cook
    stuffing = []
    stuffing << 'cheese'
    stuffing << 'grilled beef patty'
    stuffing
  end
end