code: def forward(self, x):
      if "concat_linear" in self.mode:
          return self.fuse_fn(x) + x
  
      else:
          return self.fuse_fn(x)
  
file_path: SlowFast/slowfast/models/common.py
imports: import torch
  import torch.nn
label_desc: Use image node_id 2 for calling the TwoStreamFusion obj's underlying member method code with example usage: obj.forward(x) and returns: unknown, self