code: def mock_no_sklearn():
      with patch.dict("sys.modules", {"sklearn.metrics": None}):
          yield sklearn
  
file_path: ignite/tests/ignite/contrib/metrics/test_roc_curve.py
imports: from unittest.mock import patch
  import numpy
  import pytest
  import sklearn
  import torch
  from sklearn.metrics import roc_curve
  from ignite import distributed
  from ignite.contrib.metrics.roc_auc import RocCurve
  from ignite.engine import Engine
  from ignite.exceptions import NotComputableError
  from ignite.metrics.epoch_metric import EpochMetricWarning
label_desc: Use image node_id 2 for calling a global function with example usage: mock_no_sklearn() without return types