def upd_flag_by_other_flag(flag, other_flag):
    """
    Update a flag array by another flag array.

    Take a flag list, copy it, and set the flag to 'o'utside where some
    other flag list is 'o'.

    """
    flag_new = flag.copy()
    for i, of in enumerate(other_flag):
        if of == 'o':
            flag_new[i] = 'o'
    return flag_new