added adhoc example

concurrency/confinement/adhoc/main.go

@@ -0,0 +1,27 @@
+package main
+
+import "fmt"
+
+// Confinement is the simple yet powerful idea of ensuring information is only ever
+// available from one concurrent process.
+
+// When this is achieved, a concurrent program
+//is implicitly safe and no synchronization is needed.
+
+// Ad hoc confinement is when you achieve confinement through a convention—
+// whether it be set by the languages community, the group you work within, or the
+// codebase you work within
+func main() {
+	data := make([]int, 4)
+	loopData := func(handleData chan<- int) {
+		defer close(handleData)
+		for i := range data {
+			handleData <- data[i]
+		}
+	}
+	handleData := make(chan int)
+	go loopData(handleData)
+	for num := range handleData {
+		fmt.Println(num)
+	}
+}

concurrency/iterator_error_handling/main.go

@@ -107,6 +107,8 @@ func v2() {
 		"https://insights.stackoverflow.com/survey/2017",
 		"https://hackernoon.com/top-10-python-web-frameworks-to-learn-in-2018-b2ebab969d1a",
 		"https://blog.kowalczyk.info/article/1Bkr/3-ways-to-iterate-in-go.html",
+		"A",
+		"B",
 	}
 	for result := range checkStatus(done, urls...) {
 		if result.Error != nil {