<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 async def copy_messages(self, selected: SelectedMailbox, sequence_set: SequenceSet, mailbox: str) \ -> Tuple[Optional[CopyUid], SelectedMailbox]: """Copy a set of messages into the given mailbox. See Also: `RFC 3501 6.4.7. <https://tools.ietf.org/html/rfc3501#section-6.4.7>`_ Args: selected: The selected mailbox session. sequence_set: Sequence set of message sequences or UIDs. mailbox: Name of the mailbox to copy messages into. Raises: :class:`~pymap.exceptions.MailboxNotFound` :class:`~pymap.exceptions.MailboxReadOnly` """

        ...