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 [Semaphore], allowing one more thread in. Returns [code]OK[/code] on success, [code]ERR_BUSY[/code] otherwise. Tries to wait for the [Semaphore], if its value is zero, blocks until non-zero. Returns [code]OK[/code] on success, [code]ERR_BUSY[/code] otherwise.