Empty and constant AnyPublisher extensions

AnyPublisher.swift

@available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
extension AnyPublisher {
    static var empty: Self {
        Empty(completeImmediately: false).eraseToAnyPublisher()
    }
    
    static func constant(_ value: Output) -> Self where Failure == Never {
        Just(value).eraseToAnyPublisher()
    }
}