class_docstr: BERT pooler layer.
  Based on: BERT (pytorch-transformer)
  https://github.com/huggingface/transformers
code: def __init__(self, hidden_size) -> None:
      super().__init__()
      self.dense = nn.Linear(hidden_size, hidden_size)
      self.activation = nn.Tanh()
  
imports: from __future__ import annotations
  import math
  from collections.abc import Sequence
  import torch
  from torch import nn
  from monai.config.type_definitions import PathLike
  from monai.utils import optional_import
label_desc: Use image node_id 1 to create a new Pooler object from inherited base classes: nn with example: obj = Pooler(hidden_size)