input: Write a function to find the largest sum of two numbers in a list.
  assert get_largest_sum([1, 2, 3, 4, 5]) == 9
  assert get_largest_sum([10, 20, 30, 40, 50]) == 90
  assert get_largest_sum([5, 9, 1, 3]) == 14
output: def get_largest_sum(numbers):
      if len(numbers) < 2:
          return 0
      numbers.sort(reverse=True)
      return numbers[0] + numbers[1]