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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 undefine(self):
 """Undefine the Global. Python equivalent of the CLIPS undefglobal command. The object becomes unusable after this method has been called. """

        if lib.EnvUndefglobal(self._env, self._glb) != 1:
            raise CLIPSError(self._env)

        self._env = None