# Emulate zip and padding map: build lists

def myzip(*seqs):
    seqs = [list(S) for S in seqs]
    res  = []
    while all(seqs):
        res.append(tuple(S.pop(0) for S in seqs))
    return res

def mymapPad(*seqs, pad=None):
    seqs = [list(S) for S in seqs]
    res  = []
    while any(seqs):
        res.append(tuple((S.pop(0) if S else pad) for S in seqs))
    return res

S1, S2 = 'abc', 'xyz123'
print(myzip(S1, S2))
print(mymapPad(S1, S2))
print(mymapPad(S1, S2, pad=99))