gist 1 for https://medium.com/@francesc/two-ways-of-merging-n-channels-in-go-43c0b57cd1de

main.go

func merge(cs ...<-chan int) <-chan int {
    out := make(chan int)
    
    for _, c := range cs {
        go func() {
            for v := range c {
                out <- v
            }
        }()
    }
    return out
}