* and returns it. Callers should use this to verify the request was sent as intended within the
   * given time.
   *
   * @param timeout how long to wait before giving up, in units of [unit]
   * @param unit a [TimeUnit] determining how to interpret the [timeout] parameter
   * @return the head of the request queue
   */
  @Throws(InterruptedException::class)
  fun takeRequest(