code: public User loadUserBySession (String sessionKey)
          throws PersistenceException
      {
          User user = load(_utable, "sessions", "where authcode = '" + sessionKey + "' " +
                           "AND sessions.userId = users.userId");
          if (user != null) {
              user.setDirtyMask(_utable.getFieldMask());
          }
          return user;
      }
docs: Looks up a user by a session identifier.
  
  @return the user associated with the specified session or null of no session exists with the
  supplied identifier.