input: 
  def merge_sort(list1: List[int], list2: List[int]) -> List[int]:
      """
      Merge two lists of integers into one sorted list without using the in-built sort function.
      >>> merge_sort([3, 5, 9, 1, 8], [4, 11, 7, 2])
      [1, 2, 3, 4, 5, 7, 8, 9, 11]
      """
      merged_list = list1 + list2 
      for i in range(len(merged_list)): 
          min_idx = i           
          for j in range(i+1, len(merged_list)): 
              if merged_list[min_idx] > merged_list[j]: 
                  min_idx = j 
          merged_list[i], merged_list[min_idx] = merged_list[min_idx], merged_list[i] 
      return merged_list
  
output:     merged_list = list1 + list2 
      for i in range(len(merged_list)): 
          min_idx = i           
          for j in range(i+1, len(merged_list)): 
              if merged_list[min_idx] > merged_list[j]: 
                  min_idx = j 
          merged_list[i], merged_list[min_idx] = merged_list[min_idx], merged_list[i] 
      return merged_list