original_string: private function get_unique_users() : moodle_recordset {
          global $DB;
  
          $subsql = 'SELECT DISTINCT(useridto) as id
                       FROM {message_email_messages}
                      WHERE id <= ?';
  
          $sql = "SELECT *
                    FROM {user} u
                   WHERE id IN ($subsql)";
  
          return $DB->get_recordset_sql($sql, [$this->maxid]);
      }
code: private function get_unique_users() : moodle_recordset {
          global $DB;
  
          $subsql = 'SELECT DISTINCT(useridto) as id
                       FROM {message_email_messages}
                      WHERE id <= ?';
  
          $sql = "SELECT *
                    FROM {user} u
                   WHERE id IN ($subsql)";
  
          return $DB->get_recordset_sql($sql, [$this->maxid]);
      }
code_tokens: private function get_unique_users ( ) : moodle_recordset { global $ DB ; $ subsql = 'SELECT DISTINCT(useridto) as id
                       FROM {message_email_messages}
                      WHERE id <= ?' ; $ sql = "SELECT *
                    FROM {user} u
                   WHERE id IN ($subsql)" ; return $ DB -> get_recordset_sql ( $ sql , [ $ this -> maxid ] ) ; }
docstring: Returns an array of users in the given conversation.
  
  @return moodle_recordset A moodle_recordset instance.
docstring_tokens: Returns an array of users in the given conversation .