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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 location(self):
 """Return a string uniquely identifying the event. This string can be used to find the event in the event store UI (cf. id attribute, which is the UUID that at time of writing doesn't let you easily find the event). """

        if self._location is None:
            self._location = "{}/{}-{}".format(
                self.stream,
                self.type,
                self.sequence,
            )
        return self._location