code: def test_group_of_one(self):
      y_true = [1]
      y_pred = [0]
  
      assert 1 == metrics.count(y_true, y_pred)
  
imports: import numpy
  import pytest
  import sklearn.metrics
  import fairlearn.metrics
  from fairlearn.metrics._base_metrics import _get_labels_for_confusion_matrix
label_desc: Use image node_id 2 for calling the TestCount obj's underlying member method code with example usage: obj.test_group_of_one() without return types