docs: def flushall(self, asynchronous=False):
          """
          Delete all keys in all databases on the current host.
  
          ``asynchronous`` indicates whether the operation is
          executed asynchronously by the server.
          """
          args = []
          if asynchronous:
              args.append(Token.get_token('ASYNC'))
          return self.execute_command('FLUSHALL', *args)