 	///
 	/// - parameters:
 	///   - core: The `SignalProducer` core.
-	internal init(_ core: Core) {
+	internal init(_ core: SignalProducerCore<Value, Error>) {
 		self.core = core
 	}
 

	/// - returns: A signal producer that applies signal's operator to every
	///            created signal.
	public func lift<U, F>(_ transform: @escaping (Signal<Value, Error>) -> Signal<U, F>) -> SignalProducer<U, F> {
		return SignalProducer<U, F>(.makeSignalCore {
			// Transform the `Signal`, and pass through the `didCreate` side effect and
			// the interruptHandle.
			let instance = self.core.make()

			let observerDidSetup = { startHandler(observer, Lifetime(disposable)) }
			let interruptHandle = AnyDisposable(observer.sendInterrupted)

			return SignalProducerCore.Product(signal: signal, observerDidSetup: observerDidSetup, interruptHandle: interruptHandle)
		}
	}

