fun readInt(
        firstByte: Int,
        prefixMask: Int,
      ): Int {
        val prefix = firstByte and prefixMask
        if (prefix < prefixMask) {
          return prefix // This was a single byte value.
        }

        // This is a multibyte value. Read 7 bits at a time.
        var result = prefixMask
        var shift = 0
        while (true) {
          val b = readByte()

    assertBytes(31, 224, 255, 255, 255, 7)
    assertThat(newReader(byteStream(224, 255, 255, 255, 7)).readInt(31, 31))
      .isEqualTo(0x7fffffff)
  }

  @Test
  fun prefixMask() {
    hpackWriter!!.writeInt(31, 31, 0)
    assertBytes(31, 0)
    assertThat(newReader(byteStream(0)).readInt(31, 31)).isEqualTo(31)
  }

  @Test
  fun prefixMaskMinusOne() {