Что выведет Go: слияние каналов fan-in

package main

import (
    "fmt"
    "sort"
    "sync"
)

func source(vals ...int) <-chan int {
    out := make(chan int)
    go func() {
        defer close(out)
        for _, v := range vals {
            out <- v
        }
    }()
    return out
}

func merge(cs ...<-chan int) <-chan int {
    out := make(chan int)
    var wg sync.WaitGroup
    for _, c := range cs {
        wg.Add(1)
        go func() {
            defer wg.Done()
            for v := range c {
                out <- v
            }
        }()
    }
    go func() { wg.Wait(); close(out) }()
    return out
}

func main() {
    var got []int
    for v := range merge(source(3, 1), source(2), source()) {
        got = append(got, v)
    }
    sort.Ints(got)
    fmt.Println(got, len(got))
}