def join(separator = $,)
      result = ""
      if separator
        each_with_index { |obj, i| result << separator if i > 0; result << obj.to_s }
      else
        each { |obj| result << obj.to_s }
      end
      return Erlang.from(result)
    end
def join(separator = $,)
      result = ""
      if separator
        each_with_index { |obj, i| result << separator if i > 0; result << obj.to_s }
      else
        each { |obj| result << obj.to_s }
      end
      return Erlang.from(result)
    end
Convert all the elements into strings and join them together, separated by
 `separator`. By default, the `separator` is `$,`, the global default string
 separator, which is normally `nil`.