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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 add_account(self, accounts):
 """ Adds one or more account instances to the pool. :type accounts: Account|list[Account] :param accounts: The account to be added. """

        with self.unlock_cond:
            for account in to_list(accounts):
                account.acquired_event.listen(self._on_account_acquired)
                account.released_event.listen(self._on_account_released)
                self.accounts.add(account)
                self.unlocked_accounts.append(account)
            self.unlock_cond.notify_all()