def transpose(list_in):
    """
    Shuffle/transpose a given 16 element list from
    [ 0,  1,  2,  3,
      4,  5,  6,  7,
      8,  9, 10, 11,
     12, 13, 14, 15] to
    [ 0,  4,  8, 12,
      1,  5,  9, 13,
      2,  6, 10, 14,
      3,  7, 11, 15]
    """
    list_out = []
    for i in range(4):
        for j in range(4):
            list_out.append(list_in[i + 4 * j])
    return list_out