code: def f1(self, r, p):
      if r == p == 0:
          return 0
      return 2 * r * p / (r + p)
  
file_path: allennlp/tests/training/metrics/rouge_test.py
imports: from typing import Any, Dict, Union
  import torch
  from torch.testing import assert_allclose
  from allennlp.common.testing import AllenNlpTestCase, multi_device, run_distributed_test
  from allennlp.training.metrics import ROUGE
label_desc: Use image node_id 2 for calling the RougeTest obj's underlying member method code with example usage: obj.f1(r, p) and returns: unknown, int