.writeUtf8("--")
        .writeUtf8(boundary)
        .readByteString()

    /**
     * This delimiter typically precedes all subsequent parts. It may also precede the first part
     * if the body contains a preamble.
     */
    private val crlfDashDashBoundary =
      Buffer()
        .writeUtf8("\r\n--")
        .writeUtf8(boundary)
        .readByteString()

    private var partCount = 0
    private var closed = false