# File lib/backports/1.9.1/enumerable/each_with_index.rb, line 6
    def each_with_index_with_optional_args_and_block(*args)
      return to_enum(:each_with_index, *args) unless block_given?
      idx = 0
      each(*args) { |o| yield(o, idx); idx += 1 }
      self
    end