Sorry for this simple question but I am having a little trouble understanding what is meant by poly-time reduction?
So suppose I have two algorithms A and B and then I say that A is reducible to B does polytime reduction mean that the algorithm that solves A using B as a helper runs in $O(n^k)$ for some $k$

So for example suppose 

A is the algorithm that takes input as a list of numbers and returns whether there is a sublist whose sum is 0.

B is the algorithm that takes inout as a list of numbers, an integer k and returns whether there is a sublist of length k whose sum is 0.

Then 

    def A(L):
         for i in range (1, len(L)+1)"
               if B(L, i):
                    return true
         return false

and since this A calling B as a helper runs in $O(n)$ so can this be described as a polytime reduction from A to B?