def handshakeCompleted():
        """
        Notification of the TLS handshake being completed.

        This notification fires when OpenSSL has completed the TLS handshake.
        At this point the TLS connection is established, and the protocol can
        interrogate its transport (usually an L{ISSLTransport}) for details of
        the TLS connection.

        This notification *also* fires whenever the TLS session is
        renegotiated. As a result, protocols that have certain minimum security
        requirements should implement this interface to ensure that they are
        able to re-evaluate the security of the TLS session if it changes.
        """

        Notification of the TLS handshake being completed.

        This notification fires when OpenSSL has completed the TLS handshake.
        At this point the TLS connection is established, and the protocol can
        interrogate its transport (usually an L{ISSLTransport}) for details of
        the TLS connection.

        This notification *also* fires whenever the TLS session is
        renegotiated. As a result, protocols that have certain minimum security
        requirements should implement this interface to ensure that they are
        able to re-evaluate the security of the TLS session if it changes.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/interfaces.py