update book code

eBook/examples/chapter_14/channel_idiom2.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func main() {
+	suck(pump())
+	time.Sleep(1e9)
+}
+
+func pump() chan int {
+	ch := make(chan int)
+	go func() {
+		for i := 0; ; i++ {
+			ch <- i
+		}
+	}()
+	return ch
+}
+
+func suck(ch chan int) {
+	go func() {
+		for v := range ch {
+			fmt.Println(v)
+		}
+	}()
+}