Add code

5-type-assertions-in-go/Makefile

@@ -0,0 +1,2 @@
+all:
+	go run main.go

5-type-assertions-in-go/main.go

@@ -0,0 +1,19 @@
+package main
+
+import "fmt"
+
+func main() {
+    var i interface{} = "hello"
+
+    s := i.(string)
+    fmt.Println(s)
+
+    s, ok := i.(string)
+    fmt.Println(s, ok)
+
+    f, ok := i.(float64)
+    fmt.Println(f, ok)
+
+    f = i.(float64) // panic
+    fmt.Println(f)
+}