code: def output(self, out_file):
          
          self.out_file = out_file
          out_file.write('event: ns : Nanoseconds\n')
          out_file.write('events: ns\n')
          self._output_summary()
          for entry in sorted(self.entries, key=_entry_sort_key):
              self._output_entry(entry)
docs: Write the converted entries to out_file