class_docstr: Flickr default teacher that expects open-ended descriptions of images.
code: def reset(self):
      super().reset()  # call parent reset so other fields can be set up
      self.example = None  # set up caching fields
      self.imageEpochDone = False
  
imports: from typing import Optional
  from parlai.core.params import ParlaiParser
  from parlai.core.opt import Opt
  from parlai.core.teachers import FixedDialogTeacher
  from parlai.core.image_featurizers import ImageLoader
  from parlai.utils.io import PathManager
  from .build import build
  import os
  import json
  import random
label_desc: Use image node_id 3 for calling the DefaultTeacher obj's underlying member method code with example usage: obj.reset() without return types