class_docstr: Base class for various modules which compute derivatives.
class_docstr_tok: ["Base","class","for","various","modules","which","compute","derivatives","."]
docstr: Return the VarCollection of the variables used.
docstr_tok: ["Return","the","VarCollection","of","the","variables","used","."]
code: def vars(self, scope: str = "") -> VarCollection:
      """Return the VarCollection of the variables used."""
      if scope:
          return VarCollection(
              (scope + k, v) for k, v in self.vc.items()
          )
      return VarCollection(self.vc)
  
imports: import inspect
  from typing import List, Optional, Callable, Tuple, Dict, Union
  import jax
  from objax.module import Function, Module
  from objax.typing import JaxArray
  from objax.util import repr_function, class_name
  from objax.variable import BaseState, TrainVar, VarCollection
label_desc: Use image node_id 3 for calling the _DerivativeBase obj's underlying member method code with example usage: obj.vars(scope) and returns: VarCollection, VarCollection