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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 preflight(self, program, start, stop, resolution=None, max_delay=None):
 """Preflight the given SignalFlow program and stream the output back."""

        params = self._get_params(start=start, stop=stop,
                                  resolution=resolution,
                                  maxDelay=max_delay)

        def exec_fn(since=None):
            if since:
                params['start'] = since
            return self._transport.preflight(program, params)

        c = computation.Computation(exec_fn)
        self._computations.add(c)
        return c