Gray codes generator

gray2.py

class Gray:
    def __init__(self, length):
        self.length = length

    def _right(self, n):
        if n == 1:
            yield (0,)
            yield (1,)
        else:
            for s in Gray(n-1):
                yield (0,) + s
            for s in reversed(Gray(n-1)):
                yield (1,) + s

    def _left(self, n):
        if n == 1:
            yield (1,)
            yield (0,)
        else:
            for s in Gray(n-1):
                yield (1,) + s
            for s in reversed(Gray(n-1)):
                yield (0,) + s

    def __iter__(self):
        return self._right(self.length)

    def __reversed__(self):
        return self._left(self.length)