/**
  * Use MailChimp API key to try to grab corresponding user profile to check validity of key
  *
  * @param string
  * @return bool    
  */
 function li_check_invalid_api_key($api_key)
 {
     $gr = new LI_GetResponse($api_key);
     $ping = $gr->ping();
     if (!empty($ping)) {
         $invalid_key = FALSE;
     } else {
         $invalid_key = TRUE;
     }
     return $invalid_key;
 }
 /**
  * Adds a subcsriber to a specific list
  *
  * @param   string
  * @param   string
  * @param   string
  * @param   string
  * @param   string
  * @return  int/bool
  */
 function push_contact_to_list($list_id = '', $email = '', $first_name = '', $last_name = '', $phone = '')
 {
     if (isset($this->options['li_gr_api_key']) && $this->options['li_gr_api_key'] && $list_id) {
         $gr = new LI_GetResponse($this->options['li_gr_api_key']);
         $contact_synced = $gr->addContact($list_id, $first_name . ' ' . $last_name, $email);
         return TRUE;
     }
     return FALSE;
 }