A bounded queue limits how many items it can store. The upper bound prevents an application from accepting more work than it can hold; when the queue is full, coroutine-based insertion can wait instead of adding immediately. section 12.1
Limiting a customer line
A supermarket queue configured with Queue(maxsize=1) holds one customer. A second put_nowait call cannot add another item immediately, while await queue.put(customer) provides the waiting behavior needed when the line is full. The same queue may use await queue.get() so cashiers wait for customers when the line is empty.
