class Async::Waiter

def initialize(parent: nil, finished: Async::Condition.new)

@parameter finished [Async::Condition] The condition to signal when a task completes.
@parameter parent [Interface(:async) | Nil] The parent task to use for asynchronous operations.

Create a waiter instance. 
def initialize(parent: nil, finished: Async::Condition.new)
	warn("`Async::Waiter` is deprecated, use `Async::Barrier` instead.", uplevel: 1, category: :deprecated) if $VERBOSE
	
	@finished = finished
	@done = []
	
	@parent = parent
end