new_contents: __author__ = 'zz'
  
  import re
  
  
  class SafeString:
      """
      sanitize string
      """
      dirname_pat = re.compile('\?*\\*\.*<*>*/*\|*')
  
      def sanitized_dirname(self, value, replace_by=''):
          """replace unsafe char with 'replace_by'
          """
          return self.dirname_pat.sub(replace_by, value)
subject: create utils.py