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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_mongo_version(self):
 """ Gets mongo version of the server if it is running. Otherwise return version configured in mongoVersion property """

        if self._mongo_version:
            return self._mongo_version

        mongo_version = self.read_current_mongo_version()

        if not mongo_version:
            mongo_version = self.get_configured_mongo_version()

        self._mongo_version = mongo_version

        return self._mongo_version