code: def get_charset(html):
      
      regex = r'charset=([a-zA-Z0-9-]+)?'
      pattern = re.compile(regex, re.IGNORECASE)
      if len(pattern.findall(html)) == 0:
          return 'UTF-8'
      return pattern.findall(html)[0]
docs: get charset in html page
      return : default if not exist `charset`