Find all subsets sum of an array

'''
We are pushing 0 as the first subarray sum which has no elements.
then we will take one element of the array and sum in all the previous subsets, for now
we are having one only, we will do sum of all the elments with 0 seprately and push it into
the ans array so for arr=[1,2,3] our ans was earlier=[0] and now it becomes ans=[0,0+1,0+2,0+3] then
we will go to 2 and again we will do sum of 3 with all the elements and push those as the subsets
so now ans=[0,1,2,3, 1+2, 2+2, 2+3], just keep in mind that new elements should be pushed and need
not to update the previous elements.
'''
class Solution:
    def subsetSums(self, arr):
        ans=[0]
        for i in arr:
            new_sums=[]
            for subset_sum in ans:
                new_sums.append(i+subset_sum)
            ans=ans+new_sums
        return ans