function* saga(){
    try {
        yield* worker()
    } finally {
        console.log('parent > exit')
    }
}

function* worker(){
    try {
        yield 1 // just stop here
    } finally {
        yield 2
        console.log('child > exit')
    }
}

var t = saga()
t.next() // meet the stoping point
t.return()
t.next()

console.log('child > exit')
console.log('parent > exit')

console.log('parent > exit')