def __init__(self, horiz=False, vert=False, prob=0.5):
        """
        Args:
            horiz (bool): use horizontal flip.
            vert (bool): use vertical flip.
            prob (float): probability of flip.
        """
        super(Flip, self).__init__()
        if horiz and vert:
            raise ValueError("Cannot do both horiz and vert. Please use two Flip instead.")
        if not horiz and not vert:
            raise ValueError("At least one of horiz or vert has to be True!")
        self._init(locals())

        Args:
            horiz (bool): use horizontal flip.
            vert (bool): use vertical flip.
            prob (float): probability of flip.
        
tensorpack/dataflow/imgaug/misc.py