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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 _encode_observations(self, observations):
 """Encodes observations as PNG."""

    return [
        Observation(
            self._session.obj.run(
                self._encoded_image_t.obj,
                feed_dict={self._decoded_image_p.obj: observation}
            ),
            self._decode_png
        )
        for observation in observations
    ]