def first_all_blanks(ss):
    """Find the first position that is all blank in the strings ss."""
    ss = list(ss)
    blankss = blanks(ss[0])
    for s in ss[1:]:
        blankss &= blanks(s)
    if blankss:
        return min(blankss)
    else:
        return max(len(s) for s in ss)
Find the first position that is all blank in the strings ss.
lab/parser.py