class ActiveSupport::HashWithIndifferentAccess

counters.dig(:zoo) # => nil
counters.dig(:foo, :bar) # => 1
counters.dig('foo', 'bar') # => 1

counters[:foo] = { bar: 1 }
counters = ActiveSupport::HashWithIndifferentAccess.new

either a string or a symbol:
Same as Hash#dig where the key passed as argument can be

def dig(*args)
  args[0] = convert_key(args[0]) if args.size > 0
  super(*args)
end