code: def iter_refs(self, subspace='', number=-1, etag=None):
          
          if subspace:
              args = ('git', 'refs', subspace)
          else:
              args = ('git', 'refs')
          url = self._build_url(*args, base_url=self._api)
          return self._iter(int(number), url, Reference, etag=etag)
docs: Iterates over references for this repository.
  
          :param str subspace: (optional), e.g. 'tags', 'stashes', 'notes'
          :param int number: (optional), number of refs to return. Default: -1
              returns all available refs
          :param str etag: (optional), ETag from a previous request to the same
              endpoint
          :returns: generator of :class:`Reference <github3.git.Reference>`\ s