Batch Size in Multilabel classification

Part 1 (2018)
1

So, I was doing multilabel classification as stated in [lesson2-image-models.ipynb]
(https://github.com/fastai/fastai/blob/master/courses/dl1/lesson2-image_models.ipynb).
I noticed that we havn’t specified batch size in that notebook. As in function get_data.

def get_data(sz):
    tfms = tfms_from_model(f_model, sz, aug_tfms=transforms_top_down, max_zoom=1.05)
    return ImageClassifierData.from_csv(PATH, 'train-jpg', label_csv, tfms=tfms,
                    suffix='.jpg', val_idxs=val_idxs, test_name='test-jpg')

My question is that do we not use batch size in multi label classification or we can use?