code: def test_bc_loss(self):
      prediction = torch.tensor([[10.0, 0.01]])
      target = torch.tensor([[0.0, 0.8]])
      loss = BCPlus.bc_loss(
          {
              torchbearer.PREDICTION: prediction,
              torchbearer.TARGET: target,
          }
      )
      self.assertTrue((loss - 7.81).abs().le(1e-2).all())
  
file_path: torchbearer/tests/callbacks/test_between_class.py
imports: from unittest import TestCase
  import torch
  import torchbearer
  from torchbearer.callbacks import BCPlus
label_desc: Use image node_id 2 for calling the TestBCPlus obj's underlying member method code with example usage: obj.test_bc_loss() without return types