'Loads a thumbnail into memory.
:param thumb_hash: The thumbnail hash.'

def _load_metadata(self, thumb_hash):

    file_data = self.session.lm.metadata_store.get(thumb_hash.encode('utf8'))
    if (not file_data):
        msg = (u'Metadata    not    in    store:    %s' % thumb_hash)
        raise FileNotFound(msg)
    return (file_data, len(file_data))
