input: 
  from typing import List
  
  
  def sum_of_integers(numbers: List[int]) -> int:
      """ Calculate the sum of all integers in the given list.
      >>> sum_of_integers([1, 2, 3, 4, 5])
      15
      >>> sum_of_integers([-1, 0, 1])
      0
      >>> sum_of_integers([])
      0
      >>> sum_of_integers([10, -5, 20])
      25
      """
  
output:     total = 0
      for num in numbers:
          total += num
      return total