code: def backend(self, name):
          
          try:
              backend = self.get_backend_handler_path(name)
              if backend is None:
                  raise ex.VSTUtilsException("Backend is 'None'.")  # pragma: no cover
              return self._get_baskend(backend)
          except KeyError or ImportError:
              msg = "{} ({})".format(name, self.err_message) if self.err_message else name
              raise ex.UnknownTypeException(msg)
docs: Get backend class
  
          :param name: -- name of backend type
          :type name: str
          :return: class of backend
          :rtype: class,module,object