print ()
assert vec == res2
+ vec = [1, 2, 3, 4, 9, 5, 6]
+ prd = [1, 1, 1, 1, 1, 1, 1]
+ print (vec)
+ res = preduce(len(vec), vec, prd)
+ print (res)
+ res2 = preducei(len(vec), vec, prd)
+ print (res2)
+ print ()
+ preduce_y(len(vec), vec, prd)
+ print (vec)
+ print ()
+ assert vec == res2
+