code: def setUp(self) -> None:
      self.bce_loss = MaskedBCELoss()
      self.pred = torch.FloatTensor([0.1, 0.2, 0.3, 0.4])
      self.gt = torch.FloatTensor([1, 0, 0, 0])
      self.mask = torch.BoolTensor([True, False, False, True])
  
imports: from unittest import TestCase
  import torch
  from mmocr.models.common.losses import MaskedBalancedBCELoss, MaskedBalancedBCEWithLogitsLoss, MaskedBCELoss, MaskedBCEWithLogitsLoss
label_desc: Use image node_id 1 for calling the TestMaskedBCELoss obj's underlying member method code with example usage: obj.setUp() without return types