code: def activate(self, prefix=None, backend=None):
          
          if isinstance(prefix, compat.string_types):
              self.prefix = prefix
  
          if isinstance(backend, RmoqStorageBackend):
              self.backend = backend
  
          def activate(func):
              if isinstance(func, type):
                  return self._decorate_class(func)
  
              def wrapper(*args, **kwargs):
                  with self:
                      return func(*args, **kwargs)
  
              return wrapper
  
          return activate
docs: A decorator used to activate the mocker.
  
          :param prefix:
          :param backend: An instance of a storage backend.