Add CPU profiler section

guide/heap.go

@@ -4,25 +4,13 @@ package main
 
 import (
 	"fmt"
-	"sync"
-	"sync/atomic"
 )
 
 func main() {
-	var (
-		sum int32
-		wg  = &sync.WaitGroup{}
-	)
-
-	wg.Add(2)
-	go add(&sum, 23, wg)
-	go add(&sum, 42, wg)
-	wg.Wait()
-
-	fmt.Println(sum)
+	fmt.Println(*add(23, 42))
 }
 
-func add(dst *int32, delta int32, wg *sync.WaitGroup) {
-	atomic.AddInt32(dst, delta)
-	wg.Done()
+func add(a, b int) *int {
+	sum := a + b
+	return &sum
 }