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 patkind(pattern, default=None):
    """If pattern is 'kind:pat' with a known kind, return kind."""
    return _patsplit(pattern, default)[0]