Prepend: Using `super` in a re-opened ruby class.

prepend.rb

# Original class
class Foo
  def piep
    "sag mal"
  end
end

# Methods to add/override
module FooExtension
  def piep
    "#{super} piep"
  end
end

# Reopened class
class Foo
  prepend FooExtension
end

p Foo.new.piep
# => "sag mal piep"