Merged in feature/from-pantheon (pull request #16)

code from pantheon

* code from pantheon

wp/wp-content/plugins/imagify/classes/Stats/StatInterface.php

@@ -0,0 +1,44 @@
+<?php
+namespace Imagify\Stats;
+
+defined( 'ABSPATH' ) || die( 'Cheatin’ uh?' );
+
+/**
+ * Interface to use to get and cache a stat.
+ *
+ * @since  1.9
+ * @author Grégory Viguier
+ */
+interface StatInterface {
+
+	/**
+	 * Get the stat value.
+	 *
+	 * @since  1.9
+	 * @access public
+	 * @author Grégory Viguier
+	 *
+	 * @return mixed
+	 */
+	public function get_stat();
+
+	/**
+	 * Get and cache the stat value.
+	 *
+	 * @since  1.9
+	 * @access public
+	 * @author Grégory Viguier
+	 *
+	 * @return mixed
+	 */
+	public function get_cached_stat();
+
+	/**
+	 * Clear the stat cache.
+	 *
+	 * @since  1.9
+	 * @access public
+	 * @author Grégory Viguier
+	 */
+	public function clear_cache();
+}