def advance_for_next_slice(self):
    self.slice_id += 1
Validate a view plugin, ensuring it is a view plugin and has the
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/mapreduce/model.py/TransientShardState.advance_for_next_slice--crossover with--dataset/ETHPy150Open snare/voltron/voltron/plugin.py/PluginManager.valid_view_plugin