code: def output(self):
      output_json = "Total: %d examples." % self.cnt
      for i in range(self.LEN):
          if self.top_k < self.rank[i]:
              break
          output_json += " r@%d: %.4f" % (
              self.rank[i],
              self.hits[i] / float(self.cnt),
          )
      return output_json
  
imports: import json
  import torch
label_desc: Use image node_id 4 for calling the Stats obj's underlying member method code with example usage: obj.output() and returns: output_json