input: Write a python function to count the lengths of strings in a list.
  assert count_lengths(['one', 'two', 'three', 'four']) == {'one': 3, 'two': 3, 'three': 5, 'four': 4}
  assert count_lengths(['apple', 'banana', 'cherry']) == {'apple': 5, 'banana': 6, 'cherry': 6}
  assert count_lengths(['a', 'ab', 'abc', 'abcd']) == {'a': 1, 'ab': 2, 'abc': 3, 'abcd': 4}
output: def count_lengths(strings):
      return {s: len(s) for s in strings}