class_docstr: BN that uses batch stat in inference
class_docstr_tok: ["BN","that","uses","batch","stat","in","inference"]
code: def forward(self, input):
      if self.training:
          return super().forward(input)
      return F.batch_norm(
          input, None, None, self.weight, self.bias, True, 1.0, self.eps
      )
  
imports: from torch.nn import BatchNorm2d
  from torch.nn import functional
  from .mask_rcnn_BNhead import model, dataloader, lr_multiplier, optimizer, train
label_desc: Use image node_id 1 for calling the BatchNormBatchStat obj's underlying member method code with example usage: obj.forward(input) and returns: F, super