def set_session_id(self, buf):
        """
        Set the session id to *buf* within which a session can be reused for
        this Context object.  This is needed when doing session resumption,
        because there is no way for a stored session to know which Context
        object it is associated with.

        :param bytes buf: The session id.

        :returns: None
        """
        buf = _text_to_bytes_and_warn("buf", buf)
        _openssl_assert(
            _lib.SSL_CTX_set_session_id_context(
                self._context,
                buf,
                len(buf),
            ) == 1
        )
Set the session id to *buf* within which a session can be reused for
        this Context object.  This is needed when doing session resumption,
        because there is no way for a stored session to know which Context
        object it is associated with.

        :param bytes buf: The session id.

        :returns: None