def __init__(self, horiz_frac=0, vert_frac=0,
                 border=cv2.BORDER_REPLICATE, border_value=0):
        """
        Args:
            horiz_frac (float): max abs fraction for horizontal shift
            vert_frac (float): max abs fraction for horizontal shift
            border: cv2 border method
            border_value: cv2 border value for border=cv2.BORDER_CONSTANT
        """
        assert horiz_frac < 1.0 and vert_frac < 1.0
        super(Shift, self).__init__()
        self._init(locals())

        Args:
            horiz_frac (float): max abs fraction for horizontal shift
            vert_frac (float): max abs fraction for horizontal shift
            border: cv2 border method
            border_value: cv2 border value for border=cv2.BORDER_CONSTANT
        
tensorpack/dataflow/imgaug/geometry.py