input: from typing import List
  
  def sum_list(numbers: List[int]) -> int:
      """ Calculate the sum of elements in a given list.
      >>> sum_list([1, 2, 3, 4])
      10
      >>> sum_list([-1, 0, 1])
      0
      """
output:     total = 0
      for num in numbers:
          total += num
      return total