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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 activate_program(self, program):
 """ Called by program which desires to manipulate this actuator, when it is activated. """

        self.logger.debug("activate_program %s", program)
        if program in self.program_stack:
            return

        with self._program_lock:
            self.logger.debug("activate_program got through %s", program)
            self.program_stack.append(program)
            self._update_program_stack()