class_docstr: Slowfast for ACAR-Net.
  
  Args:
      - block (`Bottleneck`):
          Bottleneck module.
      - layers (`tuple or list`):
          Number of layers at different stages.
      - alpha (`int`):
          The frame rate ratio between the Fast and Slow pathway.
      - beta (`float`):
          The ratio of channels of the Slow pathway.
      - fuse_only_conv (`bool`):
          Whether to use conv only to fuse pathways.
      - fuse_kernel_size (`int`):
          Kernel size used to fuse pathways.
      - slow_full_span (`bool`):
          Whether to span inputs for Slow pathway.
class_docstr_tok: ["Slowfast","for","ACAR-Net",".","Args",":","-","block","(","`","Bottleneck","`",")",":","Bottleneck","module",".","-","layers","(","`","tuple","or","list","`",")",":","Number","of","layers","at","different","stages",".","-","alpha","(","`","int","`",")",":","The","frame","rate","ratio","between","the","Fast","and","Slow","pathway",".","-","beta","(","`","float","`",")",":","The","ratio","of","channels","of","the","Slow","pathway",".","-","fuse_only_conv","(","`","bool","`",")",":","Whether","to","use","conv","only","to","fuse","pathways",".","-","fuse_kernel_size","(","`","int","`",")",":","Kernel","size","used","to","fuse","pathways",".","-","slow_full_span","(","`","bool","`",")",":","Whether","to","span","inputs","for","Slow","pathway","."]
code: def _make_layer_fast(
      self, block, planes, blocks, stride=1, head_conv=1, dilation=1
  ):
      downsample = None
      if stride != 1 or self.fast_inplanes != planes * block.expansion:
          downsample = nn.Sequential(
              nn.Conv3d(
                  self.fast_inplanes,
                  planes * block.expansion,
                  kernel_size=1,
                  stride=(1, stride, stride),
                  bias=False,
              )
          )
  
      layers = [
          block(
              self.fast_inplanes,
              planes,
              stride,
              downsample,
              dilation=dilation,
              head_conv=head_conv,
          )
      ]
      self.fast_inplanes = planes * block.expansion
      for _ in range(1, blocks):
          layers.append(
              block(
                  self.fast_inplanes,
                  planes,
                  dilation=dilation,
                  head_conv=head_conv,
              )
          )
  
      return nn.Sequential(*layers)
  
file_path: towhee/towhee/models/acar_net/backbone.py
imports: import torch
  from torch import nn
label_desc: Use image node_id 5 for calling the SlowFast obj's underlying member method code with example usage: obj._make_layer_fast(block, planes, blocks, stride, head_conv, dilation) and returns: nn