class_docstr: TaskNTalk basic teacher, it picks a random image and associates a random task with
  it.
  
  Metric updates and observation are to be implemented.
docstr: Process observation for metrics.
docstr_tok: ["Process","observation","for","metrics","."]
code: def observe(self, observation):
      """
      Process observation for metrics.
      """
      self.observation = observation
      # TODO(kd): update metrics
      return observation
  
imports: from parlai.core.teachers import Teacher
  from parlai.utils.io import PathManager
  from .build import build
  import json
  import os
  import random
label_desc: Use image node_id 5 for calling the AbstractTaskNTalk obj's underlying member method code with example usage: obj.observe(observation) and returns: observation