code: def shrinkage_val(self, lr):
      this_step_size = lr / np.sqrt(self.iters)
      return self.alpha * this_step_size
  
imports: import logging
  import numpy
  import torch
label_desc: Use image node_id 5 for calling the Optimizer obj's underlying member method code with example usage: obj.shrinkage_val(lr) and returns: unknown