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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def build_response(headers: Headers, key: str) -> None: """ Build a handshake response to send to the client. ``key`` comes from :func:`check_request`. """

    headers["Upgrade"] = "websocket"
    headers["Connection"] = "Upgrade"
    headers["Sec-WebSocket-Accept"] = accept(key)