- update to 0.6.4:
* The method :meth:`.Region.get_or_create_multi` will not pass to the
cache backend if no values are ultimately to be stored, based on
the use of the :paramref:`.Region.get_or_create_multi.should_cache_fn`
function. This empty dictionary is unnecessary and can cause API
problems for backends like that of Redis.
* The :attr:`.api.NO_VALUE` constant now has a fixed ``__repr__()``
output, so that scenarios where this constant's string value
ends up being used as a cache key do not create multiple values.
* A new exception class :class:`.exception.PluginNotFound` is now
raised when a particular cache plugin class cannot be located
either as a setuptools entrypoint or as a registered backend.
Previously, a plain ``Exception`` was thrown.
* Added ``replace_existing_backend`` to
:meth:`.CacheRegion.configure_from_config`.