code: def clear(self, database, callback=None):
          
          token = self._get_token()
          self._enqueue(self._PendingItem(token, BlobCommand(token=token, database=database,
                                                             content=ClearCommand()),
                                          callback))
docs: Wipe the given database. This only affects items inserted remotely; items inserted on the watch
          (e.g. alarm clock timeline pins) are not removed.
  
          :param database: The database to wipe.
          :type database: .BlobDatabaseID
          :param callback: A callback to be called on success or failure.