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