def close(callback):
    """Close this file.  Move it to its final location.

        @param callback: A no-argument callable which will be invoked
        when this file is ready to be moved to its final location.  It
        must return the segment of the path relative to per-user
        storage of the owner of this file.  Alternatively, a string
        with semantics the same as those previously described for the
        return value of the callable.

        @rtype: C{axiom.store.StoreRelativePath}
        @return: A Deferred which fires with the full path to the file
        when it has been closed, or which fails if there is some error
        closing the file.
        """
