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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 _set_exit_timeout(self, timeout, reason):
 """Set a timeout for the remainder of the session, along with an exception to raise. which is implemented by NailgunProtocol. This method may be called by a signal handler to set a timeout for the remainder of the session. If the session completes before the timeout does, the exception in `reason` is raised. Otherwise, `NailgunProtocol.ProcessStreamTimeout` is raised. :param float timeout: The length of time to time out, in seconds. :param Exception reason: The exception to raise if the session completes before the timeout occurs. """

    self._exit_timeout_start_time = time.time()
    self._exit_timeout = timeout
    self._exit_reason = reason