"DATA", "HEADERS", "PRIORITY", "RST_STREAM", "SETTINGS", "PUSH_PROMISE", "PING", "GOAWAY",
      "WINDOW_UPDATE", "CONTINUATION",
    )

  /**
   * Lookup table for valid flags for DATA, HEADERS, CONTINUATION. Invalid combinations are
   * represented in binary.
   */
  private val FLAGS = arrayOfNulls<String>(0x40) // Highest bit flag is 0x20.
  private val BINARY =
    Array(256) {