class_docstr: R(2+1)D stem is different than the default one as it uses separated 3D convolution.
  (45 1x7x7 kernels + 64 3x1x1 kernel)
code: def __init__(self):
      super(R2Plus1dStem, self).__init__(
          nn.Conv3d(
              3,
              45,
              kernel_size=(1, 7, 7),
              stride=(1, 2, 2),
              padding=(0, 3, 3),
              bias=False,
          ),
          nn.BatchNorm3d(45),
          nn.ReLU(inplace=True),
          nn.Conv3d(
              45,
              64,
              kernel_size=(3, 1, 1),
              stride=(1, 1, 1),
              padding=(1, 0, 0),
              bias=False,
          ),
          nn.BatchNorm3d(64),
          nn.ReLU(inplace=True),
      )
  
imports: import torch.nn
  from torch.hub import load_state_dict_from_url
label_desc: Use image node_id 1 to create a new R2Plus1dStem object from inherited base classes: nn with example: obj = R2Plus1dStem()