var result = peekedHeader

    if (result == null) {
      result = readHeader()
      peekedHeader = result
    }

    if (result.isEndOfData) return null

    return result
  }

  /**
   * Consume the next header in the stream and return it. If there is no header to read because we
   * have reached a limit, this returns [END_OF_DATA].
   */
  internal fun readHeader(): DerHeader {