diff --git a/examples/subclass/src/messages.h b/examples/subclass/src/messages.h
new file mode 100644
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--- /dev/null
+++ b/examples/subclass/src/messages.h
@@ -0,0 +1,33 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// This example shows Rust subclasses of C++ classes.
+// Here are the C++ classes which we're subclassing.
+
+#pragma once
+
+#include <string>
+#include <memory>
+
+class MessageProducer {
+public:
+    virtual std::string get_message() const = 0;
+    virtual ~MessageProducer() {};
+};
+
+class MessageDisplayer {
+public:
+    virtual void display_message(const std::string& message) const = 0;
+    virtual ~MessageDisplayer() {};
+};
+
+void register_cpp_thingies();
+void register_producer(const MessageProducer& producer);
+void register_displayer(const MessageDisplayer& displayer);
+
+void run_demo();