class_docstr: This class handles the parser event from opt_parser.
  When a target statement is matched, an event is triggered,
  we collected necessary information from this event and construct
  the branches as what we want to understand.
code: def get_unique_name(self, name):
      if name in self.names:
          ret_name = f"{name}_{self.names[name]}"
          self.names[name] += 1
      else:
          self.names[name] = 1
          ret_name = name
      return ret_name
  
imports: import nnabla
label_desc: Use image node_id 2 for calling the OptimizerBuilder obj's underlying member method code with example usage: obj.get_unique_name(name) and returns: ret_name