@classmethod
def open(cls, storage, name):
    """Convenience method to open a hash file given a
        :class:`whoosh.filedb.filestore.Storage` object and a name. This takes
        care of opening the file and passing its length to the initializer.
        """
    length = storage.file_length(name)
    dbfile = storage.open_file(name)
    return cls(dbfile, length)
