docstr: Returns the bias of the linear model
code: def bias(self) -> Optional[Tensor]:
      r"""
      Returns the bias of the linear model
      """
      if self.linear is None or self.linear.bias is None:
          return None
      return self.linear.bias.detach()
  
imports: from typing import Callable, cast, List, Optional
  import torch.nn
  from captum._utils.models.model import Model
  from torch import Tensor
  from torch.utils.data import DataLoader
label_desc: Use image node_id 6 for calling the LinearModel obj's underlying member method code with example usage: obj.bias() and returns: self, None