<http://a.example/S1> {
   ( <http://a.example/p1> .;
     <http://a.example/p2> .;
     <http://a.example/p3> .
   ){2,3} //
      <http://a.example/annot1> "1" //
      <http://a.example/annot2> "2" //
      <http://a.example/annot3> "3"
      %<http://shex.io/extensions/Test/>{ print("group semAct 1") %}
      %<http://shex.io/extensions/Test/>{ print("group semAct 2") %}
}