code: def snapshots(self):
          
          self.connection._check_login()
          response = self.connection._do_get("{}/{}".format(self.connection._api_url, "types/Volume/instances")).json()
          all_volumes_snapshot = []
          for volume in response:
              if volume['volumeType'] == 'Snapshot':
                  all_volumes_snapshot.append(
                      Volume.from_dict(volume)
              )
          return all_volumes_snapshot
docs: Get all Volumes of type Snapshot.  Updates every time - no caching.
          :return: a `list` of all the `ScaleIO_Volume` that have a are of type Snapshot.
          :rtype: list