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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 _depth_im_callback(self, msg):
 """Callback for handling depth images. """

        try:
            self._cur_depth_im = DepthImage(self._bridge.imgmsg_to_cv2(msg) / 1000.0, frame=self._frame)
        except:
            self._cur_depth_im = None