variable X procuct - [(x,y) for x in list1 for y in list2]

[steindl fritz]

hi list,

first - maybe sombody can help me with the english expression for the 
german word 'kreuzprodukt' - this my question is dealing with

-----------------------------------------------

example -

list1 = [1, 2]
list2 = [a, b, c]

[(x,y) for x in list1 for y in list2]

the result is the "kreuzprodukt"
[(1,a), (1,b), (1,c), (2,a), (2,b), (2,c)]

-----------------------------------------------

question -

i need to keep the number of lists variable

e.g. the next case should handle three lists

[(a1, a2, a3) for a1 in list1 for a2 in list2 for a3 in list3]

i cannot put variables into this algorythm or they don't do what i expect
maybe there is a simple solution, but i cannot find it 


<thx>

fritz
(-:fs)