How to use the bsddb3.dbutils.DeadlockWrap function in bsddb3

def _checkCursor(self):
        if self.dbc is None:
            self.dbc = _DeadlockWrap(self.db.cursor)
            if self.saved_dbc_key is not None:
                _DeadlockWrap(self.dbc.set, self.saved_dbc_key)
                self.saved_dbc_key = None

def iteritems(self):
        if not self.db:
            return
        self._kill_iteration = False
        self._in_iter += 1
        try:
            try:
                cur = self._make_iter_cursor()

                # FIXME-20031102-greg: race condition.  cursor could
                # be closed by another thread before this call.

                kv = _DeadlockWrap(cur.first)
                key = kv[0]
                yield kv

                next = getattr(cur, "next")
                while 1:
                    try:
                        kv = _DeadlockWrap(next)
                        key = kv[0]
                        yield kv
                    except _bsddb.DBCursorClosedError:
                        if self._kill_iteration:
                            raise RuntimeError('Database changed size '
                                               'during iteration.')
                        cur = self._make_iter_cursor()
                        # FIXME-20031101-greg: race condition.  cursor could
                        # be closed by another thread before this call.

def keys(self):
        self._checkOpen()
        return _DeadlockWrap(self.db.keys)

def _make_iter_cursor(self):
        cur = _DeadlockWrap(self.db.cursor)
        key = id(cur)
        self._cursor_refs[key] = ref(cur, self._gen_cref_cleaner(key))
        return cur

def _make_iter_cursor(self):
        cur = _DeadlockWrap(self.db.cursor)
        key = id(cur)
        self._cursor_refs[key] = ref(cur, self._gen_cref_cleaner(key))
        return cur

def close(self):
        self._closeCursors(save=0)
        if self.dbc is not None:
            _DeadlockWrap(self.dbc.close)
        v = 0
        if self.db is not None:
            v = _DeadlockWrap(self.db.close)
        self.dbc = None
        self.db = None
        return v

def _checkCursor(self):
        if self.dbc is None:
            self.dbc = _DeadlockWrap(self.db.cursor)
            if self.saved_dbc_key is not None:
                _DeadlockWrap(self.dbc.set, self.saved_dbc_key)
                self.saved_dbc_key = None

def _checkCursor(self):
        if self.dbc is None:
            self.dbc = _DeadlockWrap(self.db.cursor)
            if self.saved_dbc_key is not None:
                _DeadlockWrap(self.dbc.set, self.saved_dbc_key)
                self.saved_dbc_key = None
        return

def _checkCursor(self):
        if self.dbc is None:
            self.dbc = _DeadlockWrap(self.db.cursor)
            if self.saved_dbc_key is not None:
                _DeadlockWrap(self.dbc.set, self.saved_dbc_key)
                self.saved_dbc_key = None