code: def add_arxiv_eprint(self, arxiv_id, arxiv_categories):
          
          self._append_to('arxiv_eprints', {
              'value': arxiv_id,
              'categories': arxiv_categories,
          })
          self.set_citeable(True)
docs: Add arxiv eprint.
  
          :param arxiv_id: arxiv id for the current document.
          :type arxiv_id: string
  
          :param arxiv_categories: arXiv categories for the current document.
          :type arxiv_categories: list