input: def sort_even_indices(lst: list):
      """The purpose of this function is to take a list lst and return a new list where
      elements at the even indices of the list are sorted, while the odd indices remain
      unchanged.
      >>> sort_even_indices([1, 2, 3])
      [1, 2, 3]
      >>> sort_even_indices([5, 6, 3, 4])
      [3, 6, 5, 4]
      """
output:     even_indices = [i for i in range(len(lst)) if i % 2 == 0]
      even_values = [lst[i] for i in even_indices]
      even_values.sort()
      
      result = lst[:]
      for i, val in zip(even_indices, even_values):
          result[i] = val
      
      return result