input: Write a python function to return the length of each string in the list.
  assert get_lengths(["apple", "banana", "lemon", "mango"]) == [5, 6, 5, 5]
  assert get_lengths(["cat", "dog", "elephant"]) == [3, 3, 8]
  assert get_lengths([]) == []
output: def get_lengths(lst):
      return [len(word) for word in lst]