Create slightly more complex example.

This example takes the Animal class (defined in sample 1) and
reimplements it in idiomatic TypeScript. Then creates a subclass "Dog"
who can speak.

examples/walkthrough/classes/BUILD

@@ -0,0 +1,8 @@
+load("/tools/typescript/typescript", "typescript_binary")
+
+typescript_binary(
+    name = "classes",
+    deps = [
+      "main.ts"
+    ]
+)

examples/walkthrough/classes/main.ts

@@ -0,0 +1,21 @@
+// Sample inheritance in typescript.
+class Animal {
+  constructor(public name: string) { }
+
+  sound(sound: string) {
+    return this.name + " goes " + sound;
+  };
+};
+
+class Dog extends Animal {
+  constructor(name: string) {
+    super(name);
+  }
+
+  sound() {
+    return "My dog " + super.sound("bark!");
+  }
+}
+
+var colby = new Dog("Colby");
+alert(colby.sound())