asyncio.gather is used to run multiple coroutines concurrently and aggregate their results. It helps in managing several tasks simultaneously.

    import asyncio

    async def factorial(name, number):
        f = 1
        for i in range(2, number + 1):
            print(f"Task {name}: Compute factorial({i})...")
            await asyncio.sleep(1)
            f *= i
        print(f"Task {name}: factorial({number}) = {f}")
        return f

    async def main():
        # Schedule three calls *concurrently*:
        results = await asyncio.gather(
            factorial("A", 2),
            factorial("B", 3),
            factorial("C", 4),
        )
        print(results)

    asyncio.run(main())
        

    import threading

    class Singleton:
        _instance = None
        _lock = threading.Lock()  # Lock object to synchronize threads

        def __new__(cls):
            with cls._lock:  # Critical section starts
                if cls._instance is None:
                    cls._instance = super(Singleton, cls).__new__(cls)
            return cls._instance