code: def _create(self):
          
          if not os.path.exists(settings.SALMON_WHISPER_DB_PATH):
              os.makedirs(settings.SALMON_WHISPER_DB_PATH)
          archives = [whisper.parseRetentionDef(retentionDef)
                      for retentionDef in settings.ARCHIVES.split(",")]
          whisper.create(self.path, archives,
                         xFilesFactor=settings.XFILEFACTOR,
                         aggregationMethod=settings.AGGREGATION_METHOD)
docs: Create the Whisper file on disk