code: def test_unweighted(self):
      bce_obj = metrics.BinaryCrossentropy()
      y_true = np.array([1, 0, 1, 0]).reshape([2, 2])
      y_pred = np.array([1, 1, 1, 0], dtype=np.float32).reshape([2, 2])
      result = bce_obj(y_true, y_pred)
      self.assertAllClose(result, 3.9855, atol=1e-3)
  
imports: import numpy
  from keras import metrics
  from keras import testing
label_desc: Use image node_id 2 for calling the BinaryCrossentropyTest obj's underlying member method code with example usage: obj.test_unweighted() without return types