class_docstr: - Use ROUGE-2 as [PaLM 2](https://ai.google/static/documents/palm2techreport.pdf)
  - Use Mecab tokenizer for Japanese eval
code: def test_docs(self):
      return self.dataset["test"]
  
imports: import os
  import inspect
  from lm_eval.utils import rouge2_mecab
  from lm_eval.base import rf, Task
label_desc: Use image node_id 7 for calling the XLSumJa obj's underlying member method code with example usage: obj.test_docs() and returns: self