input: Write a python function to extract valid_until date and traffic_left from an HTML string using regular expressions.
  assert extract_info('Premium expires: <b>2023.12.31< Available traffic (today): <b><a href="/user/statistic.html">1.5 GB<') == ('2023.12.31', '1.5 GB')
  assert extract_info('Premium expires: <b>LifeTime< Available traffic (today): <b><a href="/user/statistic.html">500 MB<') == ('LifeTime', '500 MB')
  assert extract_info('Premium expires: <b>2022.06.15< Available traffic (today): <b><a href="/user/statistic.html">5.0 GB<') == ('2022.06.15', '5.0 GB')
output: def extract_info(html):
      import re
      valid_until_pattern = r'Premium expires: <b>(.*?)<'
      traffic_left_pattern = r'Available traffic \(today\): <b><a href="/user/statistic.html">(.*?)<'
      
      valid_until_match = re.search(valid_until_pattern, html)
      traffic_left_match = re.search(traffic_left_pattern, html)
      
      valid_until = valid_until_match.group(1) if valid_until_match else None
      traffic_left = traffic_left_match.group(1) if traffic_left_match else None
      
      return (valid_until, traffic_left)