class Placeholder:
    def __repr__(self):
        return " "

empty = Placeholder()
def align_nicely(a,b):
    maxlen = lambda seq: max(len(subseq) for subseq in seq)
    padded = lambda seq, size: seq + [empty]*(size-len(seq))
    maxwidths = [maxlen(a), maxlen(b)]
    results = []
    for item1, item2 in zip(a,b):
        results.append(padded(item1, maxwidths[0]) + padded(item2, maxwidths[1]))
    for row in results:
        print(row)

a = [[1, 2, 3], [1, 2], [1, 2, 3, 4], [1, 2, 3, 4, 5]]
b = [[1, 2, 3], [1, 2, 3], [1, 2, 3, 4], [1, 2, 3]]
align_nicely(a,b)

"""result:
[1, 2, 3,  ,  , 1, 2, 3,  ]
[1, 2,  ,  ,  , 1, 2, 3,  ]
[1, 2, 3, 4,  , 1, 2, 3, 4]
[1, 2, 3, 4, 5, 1, 2, 3,  ]
"""