## ThreadPoolExecutor
```py
__import__('concurrent').futures.ThreadPoolExecutor().submit(
   lambda x: (print(x * 2) or x ** 2 / 0), 3).result()
```

## sqlite3
```py
def SQL():
    def File(blob):
        try: import zmq; File.sock.send_pyobj(blob); return File.sock.recv_pyobj()
        except (AttributeError, zmq.Again):
            (sock := zmq.Context().socket(zmq.REQ)).connect('tcp://localhost:6106')
            sock.RCVTIMEO = 1000; File.sock = sock; return File(blob)
    import sqlite3, os; init = not os.path.exists('.db')
    (con := sqlite3.connect('.db', isolation_level=None)).row_factory = sqlite3.Row
    if init: con.executescript("""
        PRAGMA journal_mode=WAL;
        CREATE TABLE kv(k, v, t DEFAULT CURRENT_TIMESTAMP);
        CREATE INDEX index_kv_v ON kv(v);
        CREATE INDEX index_kv_k_t ON kv(k, t DESC);""")
    return type('', (), dict(__call__=lambda _, q, *p: list(map(dict, con.execute(q, p))),
        __setitem__=lambda sql, k, v: sql('INSERT INTO kv(k,v) VALUES(?,?)', k, File(v)),
        __getitem__=lambda sql, k: File(v[0]['v']) if (v := sql(
            'SELECT v FROM kv WHERE k=? ORDER BY t DESC LIMIT 1', k)) else None,
        __contains__=lambda sql, k: bool(sql('SELECT 1 FROM kv WHERE k=?', k))))()
sql = SQL()
```