docs: def name(self):
          """ Compute a name according to sub meta results names
  
          >>> gres = PlayMeta("operation")
          >>> res_plus = BasicPlayMeta(Composable(name="plus"))
          >>> res_moins = BasicPlayMeta(Composable(name="moins"))
          >>> gres.append(res_plus)
          >>> gres.append(res_moins)
          >>> gres.name
          'operation:[plus, moins]'
          """
          return "%s:[%s]" % (self._name, ", ".join(meta.name for meta in self._metas))