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 loopcv():
  import cv
  while 1:
    cv.ShowImage('hi',get_depth().astype(np.uint8))
    cv.WaitKey(10)