protected function specific_definition($mform)
 {
     global $CFG, $OUTPUT;
     $image = '<a href="http://www.sebsoft.nl" target="_new"><img src="' . $OUTPUT->pix_url('logo', 'blocks_mailchimp') . '" /></a>';
     $mform->addElement('header', 'configheader', get_string('promo', 'block_mailchimp'));
     $mform->addElement('html', get_string('promodesc', 'block_mailchimp', $image));
     $mailchimplists = \block_mailchimp\helper::call_api_lists();
     // If we're having trouble loading mailing lists.
     if ($mailchimplists === false) {
         $mform->addElement('html', "<b>" . get_string('error:load_api_lists', 'block_mailchimp') . "</b>");
         // Or if we simply have no lists yet.
     } else {
         if (empty($mailchimplists)) {
             $mform->addElement('html', "<b>" . get_string('missing_mailing_lists', 'block_mailchimp') . "</b>");
         }
     }
 }
 ';
 $helpbuttoninterest = '
     <span class="helplink">
         <a class="tooltip" aria-haspopup="true" href="' . $CFG->wwwroot . '/help.php?identifier=interest&component=block_mailchimp&lang=' . $userlang . '">
             <img class="iconhelp" src="' . $CFG->wwwroot . '/pix/help.png">
         </a>
     </span>
 ';
 $helpbuttonprofilefield = '
     <span class="helplink">
         <a class="tooltip" aria-haspopup="true" href="' . $CFG->wwwroot . '/help.php?identifier=linked_profile_field&component=block_mailchimp&lang=' . $userlang . '">
             <img class="iconhelp" src="' . $CFG->wwwroot . '/pix/help.png">
         </a>
     </span>
 ';
 $mailchimplists = \block_mailchimp\helper::call_api_lists();
 $mailchimpinterests = \block_mailchimp\helper::call_interests();
 $strheader = "";
 // If we can't make any connection with mailchimp.
 if ($mailchimplists === false) {
     $mailchimplists = array();
     $strheader = "<p><b>" . get_string("error:load_api_lists", 'block_mailchimp') . "</b></p>";
     // If we simply have no mailing lists in mailchimp yet.
 } else {
     if (empty($mailchimplists)) {
         $mailchimplists = array('' => get_string('no_lists', 'block_mailchimp'));
         $strheader = "<p><b>" . get_string("missing_mailing_lists", 'block_mailchimp') . "</b></p>";
     }
 }
 if ($mailchimpinterests === false) {
     $mailchimpinterests = array();
 /**
  * Validate data before storage
  * @param string data
  * @return mixed true if ok string if error found
  */
 public function validate($data)
 {
     global $CFG;
     $listcall = \block_mailchimp\helper::call_api_lists($data);
     if (!$listcall) {
         //There was an error calling the lists.
         return get_string('error:save_api_code', 'block_mailchimp');
     }
     return true;
 }