add version check for WordPress version less than 4.7.0

functions.php

@@ -24,6 +24,13 @@ if (version_compare('5.6.4', phpversion(), '>=')) {
     $sage_error(__('You must be using PHP 5.6.4 or greater.', 'sage'), __('Invalid PHP version', 'sage'));
 }
 
+/**
+ * Ensure compatible version of WordPress is used
+ */
+if (version_compare('4.7.0', get_bloginfo('version'), '>=')) {
+    $sage_error(__('You must be using WordPress 4.7.0 or greater.', 'sage'), __('Invalid WordPress version', 'sage'));
+}
+
 /**
  * Ensure dependencies are loaded
  */