input: Write a function to calculate the sum of a list of 15 integers. The function should take a list as input and return the sum of all its elements. If the input list is empty, the function should return 0.
  
  def sum_nums(nums):
      total = 0
      for num in nums:
          total += num
      return total
  
  assert sum_nums([1, 5, 9, 0, 2, 4, 7, 8, 6, 10, 3, 11, 12, 13, 14])==115
  assert sum_nums([])==0
  assert sum_nums([1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1])==15
output: def sum_nums(nums):
      total = 0
      for num in nums:
          total += num
      return total