code: def forward(
      model: Model[InT, OutT], X: InT, is_train: bool
  ) -> Tuple[OutT, Callable]:
      Y = model.ops.sigmoid(X, inplace=False)
  
      def backprop(dY: OutT) -> InT:
          return dY * model.ops.dsigmoid(Y, inplace=False)
  
      return Y, backprop
  
imports: from typing import Callable, Tuple
  from ..config import registry
  from ..model import Model
  from ..types import Floats2d
label_desc: Use image node_id 2 for calling a global function with example usage: forward(model, X, is_train) and returns: Y,  backprop, unknown