code: def forward(self, x: Tensor) -> Tensor:
      for blk in self.blocks:
          x = (
              checkpoint.checkpoint(blk, x)
              if self.use_checkpoint
              else blk(x)
          )
      if self.downsample is not None:
          x = self.downsample(x)
      return x
  
imports: from __future__ import annotations
  import itertools
  import warnings
  from typing import Any, Optional
  import torch
  import torch.nn.functional
  from torch import nn
  from torch.utils import checkpoint
  from kornia.contrib.models.common import DropPath, LayerNorm2d, window_partition, window_unpartition
  from kornia.core import Module, Tensor
  from kornia.core.check import KORNIA_CHECK
label_desc: Use image node_id 2 for calling the BasicLayer obj's underlying member method code with example usage: obj.forward(x) and returns: x