code: def name_variants(self):
          
          fields = 'indexed_name initials surname given_name doc_count'
          variant = namedtuple('Variant', fields)
          path = ['author-profile', 'name-variant']
          out = [variant(indexed_name=var['indexed-name'], surname=var['surname'],
                         doc_count=var.get('@doc-count'), initials=var['initials'],
                         given_name=var.get('given-name'))
                 for var in listify(chained_get(self._json, path, []))]
          return out or None
docs: List of named tuples containing variants of the author name with
          number of documents published with that variant.