input: def sort_by_length(strings):
      """ Sort a list of strings based on their lengths in ascending order.
      >>> sort_by_length(["cat", "dog", "apple", "banana"])
      ["cat", "dog", "apple", "banana"]
      >>> sort_by_length(["zebra", "ant", "bee", "giraffe"])
      ["ant", "bee", "zebra", "giraffe"]
      """
output:     return sorted(strings, key=len)