input: Write a function to sort a list of strings alphabetically and return the sorted list. If the list is empty, return an empty list.
  assert sort_strings(["Hello", "Yes", "No", "World"])==["Hello", "No", "World", "Yes"]
  assert sort_strings(["Python", "Java", "C++"])==["C++", "Java", "Python"]
  assert sort_strings(["a", "b", "c"])==["a", "b", "c"]
  assert sort_strings([])==[]
output: def sort_strings(lst):
      return sorted(lst)