def ZCache_get(ob, view_name, keywords, mtime_func, default):
    """ Fetch a cache entry for 'ob'.

        o If an object provides different views that would benefit from
          caching, it will set 'view_name', which should be treated as
          part of the cache key.  It defaults to the empty string.

        o 'keywords', if passed, will be a mapping containing keys that
          distinguish this cache entry from others even though
          'ob' and 'view_name' are the same;  the value should thus be
          part of the key for the entry.  DTMLMethods use keywords
          derived from the DTML namespace.

        o When the Cache calls 'ob.ZCacheable_getModTime',
          it should pass 'mtime_func' as an argument.  It is provided to
          allow cacheable objects to provide their own computation
          of the object's modification time.

        o If no matching entry is found, return 'default'.
        """
