input: Write a function to compute the sum of all elements in a given list. If the list is empty, return 0.
  def sum_list(input_list):
    sum = 0
    for i in input_list:
      sum += i
    return sum
  assert sum_list([1, 2, 3]) == 6
  assert sum_list([10, 20, 30, 40]) == 100
  assert sum_list([0, -1, 1]) == 0
  assert sum_list([]) == 0
output: def sum_list(input_list):
    sum = 0
    for i in input_list:
      sum += i
    return sum