'Merge data from overlays into backing file
This live merges (or "commits") contents from backing files into
overlays, thus reducing the length of a disk image chain.
:param relative: Keep backing chain referenced using relative names'

def commit(self, base, top, relative=False):

    flags = ((relative and libvirt.VIR_DOMAIN_BLOCK_COMMIT_RELATIVE) or 0)
    return self._guest._domain.blockCommit(self._disk, base, top, self.COMMIT_DEFAULT_BANDWIDTH, flags=flags)
