def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def _roots(kindpats):
    """Returns root directories to match recursively from the given patterns."""
    roots, dirs = _patternrootsanddirs(kindpats)
    return roots