code: def build_loss_fun():
      """Build the loss function."""
      return get_loss_fun()()
  
file_path: pycls/pycls/core/builders.py
imports: from pycls.core.config import cfg
  from pycls.core.net import SoftCrossEntropyLoss
  from pycls.models.anynet import AnyNet
  from pycls.models.effnet import EffNet
  from pycls.models.regnet import RegNet
  from pycls.models.resnet import ResNet
  from pycls.models.vit import ViT
label_desc: Use image node_id 4 for calling a global function with example usage: build_loss_fun() and returns: get_loss_fun