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 matchsubinclude(f):
            for prefix, matcherargs in subincludes:
                if f.startswith(prefix):
                    mf = submatchers.get(prefix)
                    if mf is None:
                        mf = match(*matcherargs)
                        submatchers[prefix] = mf

                    if mf(f[len(prefix) :]):
                        return True
            return False