values = [
    ('a', 'b', 'c'),
    ('d', 'e'),
    ('f', 'g', 'h')
]

combinations = [
    ('a', 'd', 'f'),
    ('a', 'e', 'g'),
    ('a', 'e', 'h'),
    ('b', 'd', 'f'),
    ('b', 'e', 'g'),
    ('b', 'e', 'h'),
    ('c', 'd', 'f'),
    ('c', 'e', 'g'),
    ('c', 'e', 'h')
]

values = [
    ('a', 'b', 'c'),
    ('d', 'e'),
    ('f', 'g', 'h'),
    ('i', 'j', 'k', 'l')
]

combinations = [
    ('a', 'd', 'f', 'i'),
    ('a', 'e', 'g', 'j'),
    ('a', 'e', 'h', 'k'),
    ('a', 'e', 'h', 'l'),
    ('b', 'd', 'f', 'i'),
    ('b', 'e', 'g', 'j'),
    ('b', 'e', 'h', 'k'),
    ('b', 'e', 'h', 'l'),
    ('c', 'd', 'f', 'i'),
    ('c', 'e', 'g', 'j'),
    ('c', 'e', 'h', 'k'),
    ('c', 'e', 'h', 'l'),

]

from itertools import product


def extend_to_max_len(tup, length):
    '''extends a tuple to a specified length by
    filling the empty spaces with last element of given tuple
    '''
    fill_count = length - len(tup)
    return (*tup, *[tup[-1]]*fill_count)


def non_cartesian_sum(values):
    '''Expects a list of tuples.
    gives the output according to the custom rules:
    top: first row: to be used for cartesian product with zip of remaining rows
    bottom: remaining rows: extended to longest length before zipping
    '''
    if len(values) < 2:
        print("Check length of input provided")
        return None
    top = values[0]
    bottom = values[1:]
    max_len = max(len(row) for row in bottom)
    bottom = [extend_to_max_len(row, max_len) for row in bottom]
    out = [(first, *rest) for first, rest in product(top, zip(*bottom))]
    return out


values = [
    ('a', 'b', 'c'),
    ('d', 'e'),
    ('f', 'g', 'h'),
    ('i', 'j', 'k', 'l')
]

out = non_cartesian_sum(values)
print(out)

[('a', 'd', 'f', 'i'),
 ('a', 'e', 'g', 'j'),
 ('a', 'e', 'h', 'k'),
 ('a', 'e', 'h', 'l'),
 ('b', 'd', 'f', 'i'),
 ('b', 'e', 'g', 'j'),
 ('b', 'e', 'h', 'k'),
 ('b', 'e', 'h', 'l'),
 ('c', 'd', 'f', 'i'),
 ('c', 'e', 'g', 'j'),
 ('c', 'e', 'h', 'k'),
 ('c', 'e', 'h', 'l')]

values = [
    ('a', 'b', 'c'),
    ('d', 'e'),
    ('f', 'g', 'h')
]


length_of_1 = len(values[1])
length_of_2 = len(values[2])

output = []
for item0 in values[0]:
    for i in range(max(length_of_1, length_of_2)):
        if i >= length_of_1:
            item1 = values[1][-1]
        else:
            item1 = values[1][i]
        if i >= length_of_2:
            item2 = values[2][-1]
        else:
            item2 = values[2][i]

        triple = (item0, item1, item2)
        output.append(triple)

for tup in output:
    print(tup)

values = [
    ('a', 'b', 'c'),
    ('d', 'e'),
    ('f', 'g', 'h')
]
combination = [(a,b,c) for a in values[0] for b in values[1] for c in values[2]]
print(combination)