img_path = '/Users/parthsharma/Desktop/Machine Learning/Deep Learning/CNN/Data Generators/images/dogs/dog.19.jpg'
img = image.load_img(img_path, target_size=(224, 224))
x = image.img_to_array(img)
x = np.expand_dims(x, axis=0)
x = preprocess_input(x)
what is the use of x = np.expand_dims(x, axis=0)
above