class_docstr: A negotiation teacher that loads the CaSiNo data from
  https://github.com/kushalchawla/CaSiNo.
  
  Each dialogue is converted into two datapoints, one from the perspective of each
  participant.
code: def reset(self):
      super().reset()
      self.episode_idx = self.data_offset - self.step_size
      self.dialogue_idx = None
      self.perspective = None
      self.dialogue = None
      self.output = None
      self.expected_response = None
      self.epochDone = False
  
imports: from parlai.core.teachers import Teacher
  from .build import build
  from parlai.utils.io import PathManager
  import json
  import os
  import random
  import copy
label_desc: Use image node_id 3 for calling the CasinoTeacher obj's underlying member method code with example usage: obj.reset() without return types