code: def forward(self, x: Tensor):
      assert (
          x.ndim == 2
      ), "Periodic should only be applied to first layer i.e. ndim==2"
      return self.cos_sin(
          2 * torch.pi * self.coefficients[None] * x[..., None]
      )
  
imports: from typing import List, Optional
  import torch
  from torch import Tensor, nn
  from ..constants import CATEGORICAL, FEATURES, LABEL, LOGITS, NUMERICAL
  from .custom_transformer import CLSToken, Custom_Transformer, _TokenInitialization
  from .utils import init_weights
label_desc: Use image node_id 3 for calling the Periodic obj's underlying member method code with example usage: obj.forward(x) and returns: self