Cleans the cache of this cache object.

def clean_cache(self, section=None):
        """Cleans the cache of this cache object."""
        self.remove_all_locks()
        if section is not None and "/" in section:
            raise ValueError("invalid section '{0}'".format(section))
        if section is not None:
            path = os.path.join(self._full_base, section)
        else:
            path = self._full_base
        if not os.path.exists(path):
            return
        shutil.rmtree(path)