a list is given arr = [2, 1, 10, 5] Write a function with a while operator that sums all the numbers in the list with each other ((2+1)+(2+10)+(2+5)+(1+10)+(1+5)+(10+5) ) The result should be this: res = 54

arr = [2,1,10,5]

def sum(arr):
    i = 0
    res = 0
    while i < len(arr):
        j = i + 1
        while j < len(arr):
            res += arr[i] + arr[j]
            j += 1
        i += 1
    return res
            
sum(arr)