input: Write a function to sort a list of strings in alphabetical order.
  assert sort_strings(["apple", "orange", "banana"]) == ["apple", "banana", "orange"]
  assert sort_strings(["pear", "apple", "grape", "banana"]) == ["apple", "banana", "grape", "pear"]
  assert sort_strings(["kiwi", "apple", "banana", "apple"]) == ["apple", "apple", "banana", "kiwi"]
output: def sort_strings(strings):
      return sorted(strings)