code: def add_inspire_categories(self, subject_terms, source=None):
          
          for category in subject_terms:
              category_dict = self._sourced_dict(
                  source,
                  term=category,
              )
              self._append_to('inspire_categories', category_dict)
docs: Add inspire categories.
  
          :param subject_terms: user categories for the current document.
          :type subject_terms: list
  
          :param source: source for the given categories.
          :type source: string