class_docstr: Class to manage save and restore for the model and optimizer.
docstr: Saves model and optimizer to given directory.
  
  Args:
     model_dir: Model directory to save.
     step: Current training step.
docstr_tok: ["Saves","model","and","optimizer","to","given","directory",".","Args",":","model_dir",":","Model","directory","to","save",".","step",":","Current","training","step","."]
code: def save(self, model_dir, step):
      """Saves model and optimizer to given directory.
  
      Args:
         model_dir: Model directory to save.
         step: Current training step.
      """
      save_checkpoint(self._model, self._optimizer, step, model_dir)
  
imports: import os
label_desc: Use image node_id 3 for calling the Saver obj's underlying member method code with example usage: obj.save(model_dir, step) without return types