code: def postprocess_pred(self, pred):
      pred["heatmap"] = F.sigmoid(pred["heatmap"])
      return pred
  
imports: import torch
  import torch.nn
  import torch.nn.functional
  from backbones.upsample_head import SimpleUpsampleHead
label_desc: Use image node_id 2 for calling the SimpleSegDecoder obj's underlying member method code with example usage: obj.postprocess_pred(pred) and returns: pred