def dist(a, b):
    return sum((i-j)**2 for i, j in zip(a, b))
def __init__(self, root, cwd, badfn=None, rules=[]):
        super(treematcher, self).__init__(root, cwd, badfn)
        rules = list(rules)
        self._matcher = pathmatcher.treematcher(rules)
        self._rules = rules