code: def tag_related(self, query, category=None):
          
          params = {'query': query, 'category': category}
          return self._get('related_tag.json', params)
docs: Get related tags.
  
          Parameters:
              query (str): The tag to find the related tags for.
              category (str): If specified, show only tags of a specific
                              category. Can be: General 0, Artist 1, Copyright
                              3 and Character 4.