def myFunction(base, plus):
result = []
for bas in base:
lastElem = bas[-1:][0]
for x in plus:
result.append(bas + ( (lastElem+x),) )
return result
first_elem = [(18,)]
add = [6,0,-6]
print(myFunction(first_elem, [6,0,-6]))
#[(18, 24), (18, 18), (18, 12)]
print(myFunction([(18, 24), (18, 18), (18, 12)], [6,0,-6]))
#[(18, 24, 30), (18, 24, 24), (18, 24, 18), (18, 18, 24), (18, 18, 18), (18, 18, 12), (18, 12, 18), (18, 12, 12), (18, 12, 6)]