code: def update_config(new_config):
      
      flask_app.base_config.update(new_config)
  
      # Check for changed working directory.
      if new_config.has_key('working_directory'):
          wd = os.path.abspath(new_config['working_directory'])
          if nbmanager.notebook_dir != wd:
              if not os.path.exists(wd):
                  raise IOError('Path not found: %s' % wd)
              nbmanager.notebook_dir = wd
docs: Update config options with the provided dictionary of options.