class type condition =object..end
method wait : mutex -> unitIn a multi-threaded program: Wait for the condition to be true and use the mutex to protect this situation. In a single-threaded program: this is a no-op.
method signal : unit -> unitIn a multi-threaded program: Signal one process that the condition holds. In a single-threaded program: this is a no-op.
method broadcast : unit -> unitIn a multi-threaded program: Signal all waiting processes that the condition holds. In a single-threaded program: this is a no-op.
method repr : exnMay be used internally be the implementation
