code: def forward(
      model: Model[List[Doc], List[Ints2d]], docs, is_train: bool
  ) -> Tuple[List[Ints2d], Callable]:
      columns = model.attrs["columns"]
      features: List[Ints2d] = []
      for doc in docs:
          if hasattr(doc, "to_array"):
              attrs = doc.to_array(columns)
          else:
              attrs = doc.doc.to_array(columns)[doc.start : doc.end]
          if attrs.ndim == 1:
              attrs = attrs.reshape((attrs.shape[0], 1))
          features.append(model.ops.asarray2i(attrs, dtype="uint64"))
  
      backprop: Callable[[List[Ints2d]], List] = lambda d_features: []
      return features, backprop
  
imports: from typing import Callable, List, Tuple, Union
  from thinc.api import Model, registry
  from thinc.types import Ints2d
  from ..tokens import Doc
label_desc: Use image node_id 2 for calling a global function with example usage: forward(model, docs, is_train) and returns: features,  backprop