You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: test_multiton.rb
    path of file: ./repos/facets/work/todo
    
    the code of the file until where you have to start completion: require 'test/unit'
require 'facets/multiton'

#
# EXAMPLE A - STANDARD USAGE
#
class TC_Multiton_A < Test::Unit::TestCase

  class SomeMultitonClass
    include Multiton

    attr :arg
    def initialize(arg)
      @arg = arg
    end
  end

  def test_standard

    a = SomeMultitonClass.instance(4)
    b = SomeMultitonClass.instance(4)     # a and b ar
    
  def test_multiple

    # w is the same object as x, y is the same object as z
    w,x,y,z = A.instance('A'), A.instance('A'), B.instance('B'), B.instance('B')

    yz_id = y.object_id || z.object_id

    B.class_eval {
      include Multiton
    }

    # y is not only the same object as z, but they are both the same object(s)
    # as from EXAMPLE C

    y,z = B.instance('B'), B.instance('B')

    assert_equal( y.object_id, yz_id )   # -> true
    assert_equal( z.object_id, yz_id ) # -> true

  end