code: def _build_network(self):
      self.gflus = GatedFeatureLearningUnit(
          n_features_in=self.n_features,
          n_stages=self.gflu_stages,
          feature_mask_function=t_softmax,
          dropout=self.gflu_dropout,
          feature_sparsity=self.gflu_feature_init_sparsity,
          learnable_sparsity=self.learnable_sparsity,
      )
  
imports: import torch
  import torch.nn
  from omegaconf import DictConfig
  from pytorch_tabular.models.common.layers import Add, Embedding1dLayer, GatedFeatureLearningUnit
  from pytorch_tabular.models.common.layers.activations import t_softmax
  from pytorch_tabular.utils import get_logger
  from ..base_model import BaseModel
label_desc: Use image node_id 2 for calling the GANDALFBackbone obj's underlying member method code with example usage: obj._build_network() without return types