def METHOD_NAME(self) -> Set[str]:
    assert len(self._tx_acct_key_set)
    start_ro_idx = self._get_start_ro_key_idx()
    rw_acct_key_list = self._msg.account_keys[self._msg.header.num_required_signatures:start_ro_idx]
    rw_acct_key_set = set([str(key) for key in rw_acct_key_list if str(key) not in self._tx_acct_key_set])
    return rw_acct_key_set