Added a spiral scan option

    """

    arr = []

    if style == "spiral":

        # deal with the centre image immediately

        coord = initial

        arr.append(initial)

        # for spiral, n_steps is the number of shells, and so only requires n_steps[0]

        for i in range(2, n_steps[0]+1):

            arr.append([])

            side_length = (2 * i) - 1

            # iteratively generate the next location to append

            coord = [coord[ax] + [-1,1][ax] * step_sizes[ax] for ax in range(2)]

            for direction in ([1,0],[0,-1],[-1,0],[0,1]):

                for edge_images in range(side_length-1):

                    coord = [coord[ax] + direction[ax] * step_sizes[ax] for ax in range(2)]

                    arr[i-1].append(tuple(coord))

    else:

        for i in range(n_steps[0]):  # x axis

            arr.append([])

            for j in range(n_steps[1]):  # y axis