return
				}
				if f(v) {
					r <- v
				}
			}
		}
	}(ctx, c, f, r)
	return r
}

// _Sink returns a channel that discards all values sent to it.
// This will leave a goroutine running until the context is canceled
// or the returned channel is closed.
func _Sink[Elem any](ctx context.Context) chan<- Elem {
	r := make(chan Elem)
	go func(ctx context.Context, r <-chan Elem) {
		for {