import itertools
# def siamese_data(group1,group2):
def get_true_false(group1,group2):
    f = [(g1,g2) for g2 in group2 for g1 in group1]
    t = [i for i in itertools.combinations(group1,2)]+[i for i in itertools.combinations(group2,2)]
    return (t,f)

group1 = ['a','b','c','d']
group2 = ['A','B','C','D']
get_true_false(group1,group2)