input: 
  def sum_list(input_list):
    sum = 0
    for i in input_list:
      sum += i
    return sum
  
  # Test cases
  """
  >>> sum_list([1, 2, 3, 4, 5])
  15
  >>> sum_list([-1, -2, -3, -4, -5])
  -15
  >>> sum_list([0, 0, 0, 0, 0])
  0
  >>> sum_list([])
  0
  >>> sum_list([10, 20, 30])
  60
  """
  
output:     if not input_list:
          return 0