a list is given arr = [2, 1, 10, 5] Write a function with list comprehension 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

def sum_all(arr):
  return sum([x+y for x in arr for y in arr])
  
sum_all([2, 1, 10, 5])