input: from typing import List
  
  
  def sort_by_length(words: List[str]) -> List[str]:
      """ Sorts a list of strings based on their length.
      >>> sort_by_length(["Hello", "World!", "Good", "Morning"])
      ['Good', 'Hello', 'World!', 'Morning']
      """
      words.sort(key=len)
      return words
output:     words.sort(key=len)
      return words