'Place new values in the cache under the given keys.
.. versionadded:: 0.5.0'

def set_multi(self, mapping):

    if (not mapping):
        return
    if self.key_mangler:
        mapping = dict(((self.key_mangler(k), self._value(v)) for (k, v) in mapping.items()))
    else:
        mapping = dict(((k, self._value(v)) for (k, v) in mapping.items()))
    self.backend.set_multi(mapping)
