class Ninja
  def be_awesome
    :guitar_solo
  end
end

bob = Ninja.new
p bob.be_awesome # => :guitar_solo

def bob.speak
  puts "hi"
end

bob.speak
john = bob.clone # => hi
john.speak       # => hi
matt = bob.dup
matt.speak       # => undefined method `speak' for # (NoMethodError)