What do you know about the sync package besides Atomic and Mutex?

In the sync package in Go, besides Mutex and atomic operations, there are several useful synchronization tools:

• WaitGroup — allows waiting for a group of goroutines to finish. It is used for coordinating parallel tasks.

• Once — guarantees that a specific function is executed exactly once, even if called from multiple goroutines.

• Cond — a condition variable that allows a goroutine to wait for a certain condition to occur and notify other goroutines of changes.

• RWMutex — an extension of Mutex that allows multiple readers to lock the resource simultaneously, but only one writer.

Example of using WaitGroup:

var wg sync.WaitGroup
wg.Add(2)
go func() {
    defer wg.Done()
    // work 1
}()
go func() {
    defer wg.Done()
    // work 2
}()
wg.Wait() // wait for both goroutines to finish