code: def test_metrics_matmul(second_operand, expected_result):
      """Test that `matmul` operator works and returns a compositional metric."""
      first_metric = DummyMetric([2, 2, 2])
  
      final_matmul = first_metric @ second_operand
  
      assert isinstance(final_matmul, CompositionalMetric)
  
      final_matmul.update()
      assert torch.allclose(expected_result, final_matmul.compute())
  
imports: from operator import neg, pos
  from typing import Any
  import pytest
  import torch
  from torch import tensor
  from torchmetrics.metric import CompositionalMetric, Metric
label_desc: Use image node_id 9 for calling a global function with example usage: test_metrics_matmul(second_operand, expected_result) without return types