input: Write a python function to convert a semicolon-separated string of name-age pairs into a dictionary.
  assert convert_to_dict("John,31;Alice,27;Bob,40") == {'John': '31', 'Alice': '27', 'Bob': '40'}
  assert convert_to_dict("Mike,25;Sara,30") == {'Mike': '25', 'Sara': '30'}
  assert convert_to_dict("Anna,22;Tom,33;Jerry,21") == {'Anna': '22', 'Tom': '33', 'Jerry': '21'}
output: def convert_to_dict(s):
      return dict(pair.split(',') for pair in s.split(';'))