/** The close reason from the peer, or null if this web socket has not yet read a close frame. */
  private var receivedCloseReason: String? = null

  /** True if this web socket failed and the listener has been notified. */
  private var failed = false

  /** Total number of pings sent by this web socket. */
  private var sentPingCount = 0

  /** Total number of pings received by this web socket. */

      Header("expires", ""),
      Header("from", ""),
      Header("host", ""),
      Header("if-match", ""),
      Header("if-modified-since", ""),
      Header("if-none-match", ""),
      Header("if-range", ""),
      Header("if-unmodified-since", ""),
      Header("last-modified", ""),
      Header("link", ""),
      Header("location", ""),
      Header("max-forwards", ""),
      Header("proxy-authenticate", ""),

02B6          ; mapped                 ; 0281          # 1.1  MODIFIER LETTER SMALL CAPITAL INVERTED R
02B7          ; mapped                 ; 0077          # 1.1  MODIFIER LETTER SMALL W
02B8          ; mapped                 ; 0079          # 1.1  MODIFIER LETTER SMALL Y
02B9..02C1    ; valid                                  # 1.1  MODIFIER LETTER PRIME..MODIFIER LETTER REVERSED GLOTTAL STOP

    /**
     * Creates a new web socket and immediately returns it. Creating a web socket initiates an
     * asynchronous process to connect the socket. Once that succeeds or fails, `listener` will be
     * notified. The caller must either close or cancel the returned web socket when it is no longer
     * in use.
     */
    fun newWebSocket(
      request: Request,
      listener: WebSocketListener,
    ): WebSocket
  }