code: def test_case_v1(self):
      pred = torch.tensor([1, 1, 1, 1])
      metric = MyMetric()
      metric.update(pred)
      res = metric.get_metric()
      print(res)
  
file_path: fastNLP/tests/core/metrics/test_element_cal_element.py
imports: import pytest
  from fastNLP.core.metrics import Metric
  from fastNLP.envs.imports import _NEED_IMPORT_TORCH
  from .utils import find_free_network_port, setup_ddp
label_desc: Use image node_id 1 for calling the TestElemnt obj's underlying member method code with example usage: obj.test_case_v1() without return types