class_docstr: Video 3D stem module. Provides stem operations of Conv, BN, ReLU, MaxPool
  on input data tensor for one or multiple pathways.
code: def _stem_name(self, path_idx):
      return "stem-path{}".format(path_idx)
  
imports: from typing import Sequence
  import torch.nn
  from .r2plus1_util import r2plus1_unit
label_desc: Use image node_id 3 for calling the ResNeXt3DStemMultiPathway obj's underlying member method code with example usage: obj._stem_name(path_idx) and returns: str