test: add the example.

Author: sciborrudnicki

src/test/value.spec.ts

@@ -0,0 +1,11 @@
+import { Value } from "../lib";
+
+export class TestValue<Type> extends Value<Type> {
+  public override get [Symbol.toStringTag]() {
+    return 'TestValue';
+  }
+}
+
+const value = new TestValue('test');
+
+console.log(`tag, `, value.tag);