package main

import (
    "fmt"
    "time"
)

func main() {
    // in this example we will choose between two channels
    c1 := make(chan string)
    c2 := make(chan string)

    go func() {
        time.Sleep(1 * time.Second)
        c1 <- "one"
    }()

    // each channel will receive a value after some time
    go func() {
        time.Sleep(2 * time.Second)
        c2 <- "two"
    }()

    // use select statement to wait for both values ​​at the same time,
    // printing each one as it arrives
    for i := 0; i < 2; i++ {
        select {
        case msg1 := <-c1:
            fmt.Println("received", msg1)
        case msg2 := <-c2:
            fmt.Println("received", msg2)
        }
    }
}

package main

import (
    "fmt"
    "time"
)

// the channel is used to notify main goroutine that the function completed successfully
func worker(done chan bool) {
    fmt.Println("working...")
    time.Sleep(time.Second)
    fmt.Println("done")

    done <- true // send a value to indicate that the function completed successfully
}

func main() {
    done := make(chan bool, 1) // create a buffered channel for notification
    go worker(done) // run worker

    <-done // blocked until a notification is received from the worker from the channel
           // if you remove the line <- done the program will close before the worker starts
}