code: def _add_scalars(self, tag, scalar_dict, global_step=None):
          
          timestamp = time.time()
          fw_logdir = self._file_writer.get_logdir()
          for scalar_name, scalar_value in scalar_dict.items():
              fw_tag = fw_logdir + '/' + tag + '/' + scalar_name
              if fw_tag in self._all_writers.keys():
                  fw = self._all_writers[fw_tag]
              else:
                  fw = FileWriter(logdir=fw_tag, max_queue=self._max_queue,
                                  flush_secs=self._flush_secs, filename_suffix=self._filename_suffix,
                                  verbose=self._verbose)
                  self._all_writers[fw_tag] = fw
              fw.add_summary(scalar_summary(tag, scalar_value), global_step)
              self._append_to_scalar_dict(fw_tag, scalar_value, global_step, timestamp)
docs: Adds multiple scalars to summary. This enables drawing multiple curves in one plot.
  
          Parameters
          ----------
              tag : str
                  Name for the plot.
              scalar_dict : dict
                  Values to be saved.
              global_step : int
                  Global step value to record.