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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_api_ruler(self):
 """Return the existing reader if it exists or launch a new one. Returns ------- api_ruler : org.clulab.reach.apis.ApiRuler An instance of the REACH ApiRuler class (java object). """

        if self.api_ruler is None:
            try:
                self.api_ruler = \
                    autoclass('org.clulab.reach.export.apis.ApiRuler')
            except JavaException as e:
                raise ReachOfflineReadingError(e)
        return self.api_ruler