code: def command(self, server_id, command, *args):
          
          server = self._storage[server_id]
          try:
              if args:
                  result = getattr(server, command)(*args)
              else:
                  result = getattr(server, command)()
          except AttributeError:
              raise ValueError("Cannot issue the command %r to server %s"
                               % (command, server_id))
          self._storage[server_id] = server
          return result
docs: run command
          Args:
              server_id - server identity
              command - command which apply to server