code: def __call__(
      self,
      gradient: ep.Tensor,
  ) -> ep.Tensor:
      return self.stepsize * gradient
  
imports: from typing import Union, Any, Optional, Callable, Tuple
  from abc import ABC, abstractmethod
  import eagerpy
  from ..devutils import flatten
  from ..devutils import atleast_kd
  from ..types import Bounds
  from ..models.base import Model
  from ..criteria import Misclassification, TargetedMisclassification
  from ..distances import l1, l2, linf
  from .base import FixedEpsilonAttack
  from .base import T
  from .base import get_criterion
  from .base import raise_if_kwargs
  from .base import verify_input_bounds
label_desc: Use image node_id 2 for calling the GDOptimizer obj's underlying member method code with example usage: obj.__call__(gradient) and returns: unknown