code: def _write(self):
          
          self.json_file.seek(0)
          self.json_file.truncate()
          dump = json.dumps(self.backup_dict)
          dump_c = zlib.compress(dump.encode('utf-8'))
          self.json_file.write(dump_c)
docs: Writes data from backup_dict property in serialized and compressed form
          to backup file pointed in json_file property.