input: Write a function to sort a list of strings first by length in descending order, and then alphabetically in ascending order.
  assert sort_strings(["hello", "world", "from", "code"]) == ["world", "hello", "from", "code"]
  assert sort_strings(["apple", "bat", "at", "ball", "cat"]) == ["apple", "ball", "bat", "cat", "at"]
  assert sort_strings(["zebra", "dog", "elephant", "cat", "apple"]) == ["elephant", "zebra", "apple", "cat", "dog"]
output: def sort_strings(strings):
      return sorted(strings, key=lambda x: (-len(x), x))