code: def attr_list(label=None, kwargs=None, attributes=None):
      
      content = a_list(label, kwargs, attributes)
      if not content:
          return ''
      return ' [%s]' % content
docs: Return assembled DOT attribute list string.
  
      Sorts ``kwargs`` and ``attributes`` if they are plain dicts (to avoid
      unpredictable order from hash randomization in Python 3 versions).
  
      >>> attr_list()
      ''
  
      >>> attr_list('spam spam', kwargs={'eggs': 'eggs', 'ham': 'ham ham'})
      ' [label="spam spam" eggs=eggs ham="ham ham"]'
  
      >>> attr_list(kwargs={'spam': None, 'eggs': ''})
      ' [eggs=""]'