def iterate_multi(meth, *args)
  case meth
  when Symbol
    enums = args.map { |arg|
      to_enum(meth, *arg)
    }
  else
    enums = args.map { |arg|
      meth.to_enum(:call, *arg)
    }
  end

  ended = false
  retvals = Array.new(enums.size)

  while true
    yargs = enums.map.with_index { |enum, i|
      begin
        enum.next
      rescue StopIteration => e
        retvals[i] = e.result
        ended = true
      end
    }

    return retvals if ended

    yield(*yargs)
  end
end