The RAM cache key is **global** and not restricted to the context of one function.
Therefore it is **very** important to make the result of the cache key function specific to the cached function.
Best practice is to include the dottedname of the cached function in the cache key as prefix, so that the cache does not apply in other functions. --> [Example](https://github.com/4teamwork/opengever.core/blob/master/opengever/ogds/base/contact_info.py#L572)