def save(self, filename=None):
        filename = Path(filename) if filename is not None else self.filename
        with filename.open("w") as f:
            f.write(self.yaml)
def __init__(self, root, cwd, badfn=None, relativeuipath=True):
        self._root = root
        self._cwd = cwd
        if badfn is not None:
            self.bad = badfn
        self._relativeuipath = relativeuipath