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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 apply_environ(self):
 """Apply changes to target environ. """

        if self.manager is None:
            raise RezSystemError("You must call 'set_manager' on a Python rex "
                                 "interpreter before using it.")

        self.target_environ.update(self.manager.environ)