code: def test_corner_case():
      """Issue: https://github.com/Lightning-AI/torchmetrics/issues/1693."""
      # edge case: class 2 is not present in the target AND the prediction
      target = torch.tensor([0, 1, 0, 0])
      preds = torch.tensor([0, 1, 0, 1])
  
      metric = MulticlassJaccardIndex(num_classes=3, average="none")
      res = metric(preds, target)
      assert torch.allclose(
          res, torch.tensor([2.0 / 3.0, 0.5000, 0.0000])
      )
  
      metric = MulticlassJaccardIndex(num_classes=3, average="macro")
      res = metric(preds, target)
      assert torch.allclose(res, torch.tensor(0.5833333))
  
      target = torch.tensor([0, 1])
      pred = torch.tensor([0, 1])
      out = torch.tensor([1, 1, 0, 0, 0, 0, 0, 0, 0, 0]).float()
      res = multiclass_jaccard_index(pred, target, num_classes=10)
      assert torch.allclose(res, torch.ones_like(res))
      res = multiclass_jaccard_index(
          pred, target, num_classes=10, average="none"
      )
      assert torch.allclose(res, out)
  
imports: from functools import partial
  import numpy
  import pytest
  import torch
  from scipy.special import expit
  from sklearn.metrics import confusion_matrix
  from sklearn.metrics import jaccard_score
  from torchmetrics.classification.jaccard import BinaryJaccardIndex, JaccardIndex, MulticlassJaccardIndex, MultilabelJaccardIndex
  from torchmetrics.functional.classification.jaccard import binary_jaccard_index, multiclass_jaccard_index, multilabel_jaccard_index
  from torchmetrics.metric import Metric
  from unittests import NUM_CLASSES, THRESHOLD
  from unittests.classification.inputs import _binary_cases, _multiclass_cases, _multilabel_cases
  from unittests.helpers.testers import MetricTester, inject_ignore_index, remove_ignore_index
label_desc: Use image node_id 4 for calling a global function with example usage: test_corner_case() without return types