{
  "type": "Schema",
  "shapes": [
    { "type": "ShapeDecl",
    "id": "http://example.org/S",
    "shapeExpr": {
      "type": "Shape",
      "expression": {
        "type": "TripleConstraint",
        "predicate": "http://example.org/a",
        "valueExpr": {
          "type": "Shape",
          "expression": {
            "type": "TripleConstraint",
            "predicate": "http://example.org/b",
            "valueExpr": "http://example.org/S"
          }
        }
      }
    } }
  ],
  "@context": "http://www.w3.org/ns/shex.jsonld"
}