matrix = [[1, 2, 3, 4],
          [5, 6, 7, 8],
          [9, 1, 2, 3],
          [4, 5, 6, 7]]


def create_new_2d_list(height, width):
    pass


def main():
    # how do I get at the 9?
    # how do I loop through the third row?
    # how do I loop through the second column?
    pass


main()
