for1.py

# dummy implementation just to show the intent
def for1(list1, list2, list3):
    for i in list1:
        for j in list2:
            for k in list3:
                yield (i, j, k)
                
for i in for1(['a', 'b', 'c'], [1, 2], ['asd']):
    print(i)
    
# outputs
# ('a', 1, 'asd')
# ('a', 2, 'asd')
# ('b', 1, 'asd')
# ('b', 2, 'asd')
# ('c', 1, 'asd')
# ('c', 2, 'asd')