'dump image number `image_index` in data `index` to a random
file in `output_directory`.'

def __init__(self, dataloader, index, image_index, outshape, output_directory=None, *args, **kwargs):

    super(DumpImage, self).__init__(dataloader, index=index, *args, **kwargs)
    self.outshape = outshape
    self.image_index = image_index
    self.output_directory = (output_directory or '/tmp')
    if (self.output_directory[(-1)] != '/'):
        self.output_directory += '/'
