code: def tfmer_clas_split(model:nn.Module) -> List[nn.Module]:
      "Split a RNN `model` in groups for differential learning rates."
      encoder = model[0].module
      n = len(encoder.layers)//3
      groups = [[encoder.encoder], list(encoder.layers[:n]), list(encoder.layers[n:2*n]), list(encoder.layers[2*n:])]
      return groups + [[model[1]]f tfmer_clas_split(model:nn.Module) -> List[nn.Module]:
      "Split a RNN `model` in groups for differential learning rates."
      encoder = model[0].module
      n = len(encoder.layers)//3
      groups = [[encoder.encoder], list(encoder.layers[:n]), list(encoder.layers[n:2*n]), list(encoder.layers[2*n:])]
      return groups + [[model[1]]]
docs: Split a RNN `model` in groups for differential learning rates.