╰─ pry
[1] pry(main)> class Poop
[1] pry(main)*   def [](arg)
[1] pry(main)*     arg.to_s + " world"
[1] pry(main)*   end
[1] pry(main)* end
=> :[]
[2] pry(main)> Poop.new["hello"]
=> "hello world"