diff --git a/classes/local/base.php b/classes/local/base.php
new file mode 100644
index 0000000..8199834
--- /dev/null
+++ b/classes/local/base.php
@@ -0,0 +1,23 @@
+<?php
+/**
+ * Base class.
+ *
+ * @package auth_ouopenid
+ * @author  Nick Freear, 07-March-2018.
+ * @copyright © 2018 The Open University.
+ *
+ * @link  https://docs.moodle.org/dev/Data_manipulation_API#Inserting_Records
+ */
+
+namespace auth_ouopenid\local;
+
+class base {
+
+  /** Output arbitrary data, eg. to HTTP header.
+  */
+  public static function debug($obj) {
+      static $count = 0;
+      header(sprintf('Xx-auth-ou-openid-%02d: %s', $count, json_encode($obj)));
+      $count++;
+  }
+}
diff --git a/classes/local/conditional_embedded_survey.php b/classes/local/conditional_embedded_survey.php
index a0fd960..094303f 100644
--- a/classes/local/conditional_embedded_survey.php
+++ b/classes/local/conditional_embedded_survey.php
@@ -11,7 +11,9 @@
 
 namespace auth_ouopenid\local;
 
-class conditional_embedded_survey {
+use auth_ouopenid\local\base;
+
+class conditional_embedded_survey extends base {
 
   const CONFIG_KEY = 'auth_ouopenid_conditional_survey_activity';
   const MOD_TYPE_NAME = 'assign';   // 'mod/assign'
@@ -130,13 +132,4 @@ protected function course_module_completion() {
 
     self::_debug([ __METHOD__, $lastinsertid ]);
   }
-
-  /** Output arbitrary data, eg. to HTTP header.
-  */
-  protected static function _debug($obj)
-  {
-      static $count = 0;
-      header(sprintf('X-auth-ou-cond-%02d: %s', $count, json_encode($obj)));
-      $count++;
-  }
 }
diff --git a/classes/local/tesla_consent.php b/classes/local/tesla_consent.php
index 66796bb..a351544 100644
--- a/classes/local/tesla_consent.php
+++ b/classes/local/tesla_consent.php
@@ -11,7 +11,9 @@
 
 namespace auth_ouopenid\local;
 
-class tesla_consent {
+use auth_ouopenid\local\base;
+
+class tesla_consent extends base {
 
   const DB_TABLE = 'local_tesla_agreement';
   const AGREE_VERSION = '2.0';
@@ -46,7 +48,8 @@ public static function agree( $userid = null, $version = self::AGREE_VERSION ) {
       'accepted' => true,
     ], false);
 
-    // self::_debug([ __METHOD__, $lastinsertid ]);
+    self::_debug([ __METHOD__, $lastinsertid ]);
+
     return $lastinsertid;
   }
 
diff --git a/classes/user_event_observer.php b/classes/user_event_observer.php
index 39adb4e..d198c8d 100644
--- a/classes/user_event_observer.php
+++ b/classes/user_event_observer.php
@@ -10,10 +10,12 @@
 namespace auth_ouopenid;
 
 require_once __DIR__ . '/../../../vendor/autoload.php';
+require_once __DIR__ . '/local/base.php';
 
 use IET_OU\Moodle\Auth\Ouopenid\Db\User as OuUser;
+use auth_ouopenid\local\base;
 
-class user_event_observer {
+class user_event_observer extends base {
 
     public static function core_user_created($event) {
 
@@ -22,7 +24,7 @@ public static function core_user_created($event) {
 
         // Was: self::redirect($user_created = true, __FUNCTION__);
 
-        OuUser::debug(__FUNCTION__);
+        self::debug(__FUNCTION__);
     }
 
     public static function core_user_loggedin($event) {
@@ -35,7 +37,7 @@ public static function embed_event_data(\core\event\base $event) {
                 json_encode( $event->get_data() ) .
                 "</script>\n";
         } else {
-            OuUser::debug([ __FUNCTION__, $event->get_data() ]);
+            self::debug([ __FUNCTION__, $event->get_data() ]);
         }
     }
 
@@ -46,15 +48,15 @@ protected static function redirect($user_created, $fn) {
         $redirects  = isset($CFG->auth_ouopenid_redirects) ? $CFG->auth_ouopenid_redirects : null;
 
         if (! isset($USER->username)) {
-            return OuUser::debug([ __FUNCTION__, 'Warning, no username.', $USER ]);
+            return self::debug([ __FUNCTION__, 'Warning, no username.', $USER ]);
         }
 
         $ou_profile = OuUser::getUser($USER->username);
 
-        OuUser::debug([ __FUNCTION__, $fn, $redirects, $ou_profile ]);
+        self::debug([ __FUNCTION__, $fn, $redirects, $ou_profile ]);
 
         if (! $redirects || ! $enabled) {
-            return OuUser::debug([ __FUNCTION__, 'Warning, redirect is disabled (or missing).', $redirects ]);
+            return self::debug([ __FUNCTION__, 'Warning, redirect is disabled (or missing).' ]);
         }
 
         $url = OuUser::getRedirectUrl($ou_profile, $user_created ? 'newenrol' : 'return');
diff --git a/survey-end/index.php b/survey-end/index.php
index d9a76da..8402e7a 100644
--- a/survey-end/index.php
+++ b/survey-end/index.php
@@ -9,9 +9,11 @@
 
 // For 'print_string()' language support!
 require_once __DIR__ . '/../../../config.php';
+require_once __DIR__ . '/../classes/local/base.php';
 require_once __DIR__ . '/../classes/local/conditional_embedded_survey.php';
 require_once __DIR__ . '/../classes/local/tesla_consent.php';
 
+use auth_ouopenid\local\conditional_embedded_survey;
 use auth_ouopenid\local\tesla_consent;
 
 define( 'OUOP_STRING', 'auth_ouopenid' );