Greetings, I want to add a method to the Array class. #(‘abc’ ‘def’) join => ‘abcdef’ #(‘abc’ ‘def’) join: $/ => ‘abc/def’ I am afraid that if I add it to Array directly, it will get lost in a new update. I want to keep it in my project area. In ruby, this is called a “mix in”. How can I do this? Sincerely, Joe.