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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 get_web_session_cookies(self):
 """Get web authentication cookies via WebAPI's ``AuthenticateUser`` .. note:: The cookies are valid only while :class:`.SteamClient` instance is logged on. :return: dict with authentication cookies :rtype: :class:`dict`, :class:`None` """

        if not self.logged_on: return None

        resp = self.send_job_and_wait(MsgProto(EMsg.ClientRequestWebAPIAuthenticateUserNonce), timeout=7)

        if resp is None: return None

        skey, ekey = generate_session_key()

        data = {
            'steamid': self.steam_id,
            'sessionkey': ekey,
            'encrypted_loginkey': symmetric_encrypt(resp.webapi_authenticate_user_nonce.encode('ascii'), skey),
        }

        try:
            resp = webapi.post('ISteamUserAuth', 'AuthenticateUser', 1, params=data)
        except Exception as exp:
            self._LOG.debug("get_web_session_cookies error: %s" % str(exp))
            return None

        return {
            'steamLogin': resp['authenticateuser']['token'],
            'steamLoginSecure': resp['authenticateuser']['tokensecure'],
        }