code: def name_variants(self):
          
          out = []
          variant = namedtuple('Variant', 'name doc_count')
          for var in chained_get(self._json, ['name-variants', 'name-variant'], []):
              new = variant(name=var['$'], doc_count=var.get('@doc-count'))
              out.append(new)
          return out
docs: A list of namedtuples representing variants of the affiliation name
          with number of documents referring to this variant.