feat: add Go modules and timeout handling examples

- Add `go.mod` file for module initialization in solution01
- Implement a basic Go program in solution01 to demonstrate handling timeouts with `time.After`
- Add `go.mod` file for module initialization in solution02
- Implement a basic Go program in solution02 to demonstrate handling timeouts with `context.WithTimeout`

Signed-off-by: appleboy <[email protected]>

example56-context-timeout/solution01/go.mod

@@ -0,0 +1,3 @@
+module example
+
+go 1.23.1

example56-context-timeout/solution01/main.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"time"
+)
+
+func main() {
+	output := make(chan int, 30)
+
+	go func() {
+		for i := 0; i < 30; i++ {
+			output <- i
+			time.Sleep(100 * time.Millisecond)
+		}
+	}()
+
+	timeout := time.After(1 * time.Second)
+	// how to fix the timeout issue?
+	for {
+		select {
+		case val := <-output:
+			select {
+			case <-timeout:
+				println("reached timeout, but still have data to process")
+				return
+			default:
+			}
+			// simulate slow consumer
+			time.Sleep(500 * time.Millisecond)
+			println("output:", val)
+		// how to fix the timeout issue?
+		case <-timeout:
+			println("timeout")
+			return
+		}
+	}
+}

example56-context-timeout/solution02/go.mod

@@ -0,0 +1,3 @@
+module example
+
+go 1.23.1

example56-context-timeout/solution02/main.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"context"
+	"time"
+)
+
+func main() {
+	output := make(chan int, 30)
+
+	go func() {
+		for i := 0; i < 30; i++ {
+			output <- i
+			time.Sleep(100 * time.Millisecond)
+		}
+	}()
+
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+	defer cancel()
+	// how to fix the timeout issue?
+	for {
+		select {
+		case val := <-output:
+			if ctx.Err() != nil {
+				println("reached timeout, but still have data to process")
+				return
+			}
+			// simulate slow consumer
+			time.Sleep(500 * time.Millisecond)
+			println("output:", val)
+		// how to fix the timeout issue?
+		case <-ctx.Done():
+			println("timeout")
+			return
+		}
+	}
+}