let publisherE = PassthroughSubject<String, Never>()
let publisherF = PassthroughSubject<String, Never>()

let publishers = PassthroughSubject<PassthroughSubject<String, Never>,Never>()

publishers.switchToLatest().sink {
    print($0)
}

publishers.send(publisherE)
publisherE.send("Publisher E - Value 1") //Publisher E - Value 1
publisherE.send("Publisher E - Value 2") //Publisher E - Value 2

publishers.send(publisherF) // switching to publisher 2
publisherF.send("Publisher F - Value 1") //Publisher F - Value 1
publisherE.send("Publisher E - Value 3") //