def __init__(self, func, coord_func=None):
        """
        Args:
            func: a function which takes an image array and return an augmented one
            coord_func: optional. A function which takes coordinates and return augmented ones.
                Coordinates should be Nx2 array of (x, y)s.
        """
        super(MapImage, self).__init__()
        self.func = func
        self.coord_func = coord_func

        Args:
            func: a function which takes an image array and return an augmented one
            coord_func: optional. A function which takes coordinates and return augmented ones.
                Coordinates should be Nx2 array of (x, y)s.
        
tensorpack/dataflow/imgaug/meta.py