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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 get_peers_public_keys(self):
 """Returns the list of public keys for all peers."""

        with self._lock:
            # Use a generator inside the list comprehension to filter out None
            # values in a single pass
            return [key for key
                    in (self._network.connection_id_to_public_key(peer)
                        for peer
                        in copy.copy(self._peers))
                    if key is not None]