code: def sync_target(self, decay=None):
      if decay is None:
          decay = 1.0 - self.tau
      for param, target_param in zip(
          self.model.parameters(), self.target_model.parameters()
      ):
          target_param.data.copy_(
              (1 - decay) * param.data + decay * target_param.data
          )
  
file_path: PARL/parl/algorithms/torch/ddpg.py
imports: import torch
  import torch.nn.functional
  from copy import deepcopy
  import parl
  from parl.utils.utils import check_model_method
label_desc: Use image node_id 6 for calling the DDPG obj's underlying member method code with example usage: obj.sync_target(decay) without return types