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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:
 async def fetch_messages(self, selected: SelectedMailbox, sequence_set: SequenceSet, attributes: FrozenSet[FetchAttribute]) \ -> Tuple[Iterable[Tuple[int, MessageInterface]], SelectedMailbox]: """Get a list of loaded message objects corresponding to given sequence set. Args: selected: The selected mailbox session. sequence_set: Sequence set of message sequences or UIDs. attributes: Fetch attributes for the messages. Raises: :class:`~pymap.exceptions.MailboxNotFound` """

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