class Struct

def dig(key, *rest)
  return self[key] if key.respond_to?(:to_int)
  return nil unless respond_to?(key)
  val = public_send(key)
  return val if rest.empty? || val == nil
  raise TypeError, "#{val.class} does not have #dig method" unless val.respond_to? :dig
  val.dig(*rest)
end