input: 
  from typing import List
  
  def merge_sorted_lists(list1: List[int], list2: List[int]) -> List[int]:
      """Merges two sorted lists into one sorted list.
      
      >>> merge_sorted_lists([1, 3, 5], [2, 4, 6])
      [1, 2, 3, 4, 5, 6]
      
      >>> merge_sorted_lists([], [1, 2, 3])
      [1, 2, 3]
      
      >>> merge_sorted_lists([1, 1, 1], [1, 1])
      [1, 1, 1, 1, 1]
      """
      return sorted(list1 + list2)
  
output:     
      merged_list = []
      i, j = 0, 0
      while i < len(list1) and j < len(list2):
          if list1[i] < list2[j]:
              merged_list.append(list1[i])
              i += 1
          else:
              merged_list.append(list2[j])
              j += 1
      merged_list.extend(list1[i:])
      merged_list.extend(list2[j:])
      return merged_list
  