code: def relative_private_config_file(self):
          
  
          path = os.path.join(self.working_dir, 'private-config.cfg')
          if os.path.exists(path):
              return 'private-config.cfg'
          else:
              return None
docs: Returns the private-config file relative to the project directory.
  
          :returns: path to private-config file. None if the file doesn't exist