A synchronization Semaphore. A synchronization Semaphore. Element used to synchronize multiple [Thread]s. Initialized to zero on creation. Be careful to avoid deadlocks. For a binary version, see [Mutex]. Lowers the [code]Semaphore[/code], allowing one more thread in. Returns [constant OK] on success, [constant ERR_BUSY] otherwise. Tries to wait for the [code]Semaphore[/code], if its value is zero, blocks until non-zero. Returns [constant OK] on success, [constant ERR_BUSY] otherwise.