spiral_form

def spiral_form(array):
    if not array:
        return

    n = len(array)
    m = len(array[0])

    result = []

    left = 0  # start column index
    right = m - 1  # end column index
    up = 0  # start row index
    down = n - 1  # end row index

    while len(result) < n * m:
        for i in range(left, right + 1):
            result.append(array[left][i])

        for i in range(up + 1, down + 1):
            result.append(array[i][right])

        if len(result) < n * m:

            for i in range(right - 1, left - 1, -1):
                result.append(array[down][i])

            for i in range(down - 1, up, -1):
                result.append(array[i][left])

        left += 1
        right -= 1
        down -= 1
        up += 1

    return result