package main

import (
    "context"
    "fmt"
    "time"
)

func main() {
    count := func(ctx context.Context, dst chan<- int) {
        n := 1
        for {
            select {
            case dst <- n:
                n++
            case <-ctx.Done():
                fmt.Println("not leaking")
                return
            }
        }
    }

    ctx, cancel := context.WithCancel(context.Background())
    defer cancel()

    ints := make(chan int)
    go count(ctx, ints)
    for n := range ints {
        fmt.Println(n)
        if n == 5 {
            cancel()
            break
        }
    }

    time.Sleep(time.Minute)
}