code: def set_cell_anchors(self, dtype, device):
      # type: (torch.dtype, torch.device) -> None
      if self.cell_anchors is not None:
          cell_anchors = self.cell_anchors
          assert cell_anchors is not None
          # suppose that all anchors have the same device
          # which is a valid assumption in the current state of the codebase
          if cell_anchors[0].device == device:
              return
  
      # 根据提供的sizes和aspect_ratios生成anchors模板
      # anchors模板都是以(0, 0)为中心的anchor
      cell_anchors = [
          self.generate_anchors(sizes, aspect_ratios, dtype, device)
          for sizes, aspect_ratios in zip(
              self.sizes, self.aspect_ratios
          )
      ]
      self.cell_anchors = cell_anchors
  
imports: from typing import List, Optional, Dict, Tuple
  import torch
  from torch import nn, Tensor
  from torch.nn import functional
  import torchvision
  from .None import det_utils
  from .None import boxes
  from .image_list import ImageList
label_desc: Use image node_id 3 for calling the AnchorsGenerator obj's underlying member method code with example usage: obj.set_cell_anchors(dtype, device) without return types