Ruby/Class/freeze

class MyClass
  def my_method
    puts "This is the only method allowed in MyClass."
  end
  MyClass.freeze
end
class MySubclass < MyClass
  def my_method
    "This is only one of the methods available in MySubclass."
  end
  def my_other_method
    "This is the other one."
  end
end
MySubclass.new.my_method

class MyClass
  def my_method
    puts "This is the only method allowed in MyClass."
  end
  MyClass.freeze
end
class MyClass
  def my_method
    puts "I like this implementation of my_method better."
  end
end