input: Write a function to sort a list of strings based on their length. The function should take a list of strings as input and return the sorted list.
  assert sort_strings_by_length(["Hello", "World!", "Good", "Morning"]) == ["Good", "Hello", "World!", "Morning"]
  assert sort_strings_by_length(["I", "am", "learning", "Python"]) == ["I", "am", "Python", "learning"]
  assert sort_strings_by_length([]) == []
output: def sort_strings_by_length(strings):
      return sorted(strings, key=len)