first commit

inc/core/Serviceable.php

@@ -0,0 +1,18 @@
+<?php // phpcs:ignore WordPress.Files.FileName.NotHyphenatedLowercase
+/**
+ * Service interface contract.
+ *
+ * @package PressBook
+ */
+
+namespace PressBook;
+
+/**
+ * Interface for service instance.
+ */
+interface Serviceable {
+	/**
+	 * Register a service.
+	 */
+	public function register();
+}