code: def _get_user(self, username):
          
          if username is None:
              return {}
          ret = {}
          for b in self.backends:
              try:
                  tmp = self.backends[b].get_user(username)
              except UserDoesntExist as e:
                  self._handle_exception(e)
                  tmp = {}
              self._merge_user_attrs(tmp, ret, b)
  
          cherrypy.log.error(
              msg="user '" + username + "' attributes " + str(ret),
              severity=logging.DEBUG
          )
          return ret
docs: get user attributes
          @str username: user to get
          @rtype: dict, {<attr>: <value>}