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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 restore_instances(self, instances):
 """Restore a set of instances into the CLIPS data base. The Python equivalent of the CLIPS restore-instances command. Instances can be passed as a set of strings or as a file. """

        instances = instances.encode()

        if os.path.exists(instances):
            ret = lib.EnvRestoreInstances(self._env, instances)
            if ret == -1:
                raise CLIPSError(self._env)
        else:
            ret = lib.EnvRestoreInstancesFromString(self._env, instances, -1)
            if ret == -1:
                raise CLIPSError(self._env)

        return ret