{
  "type": "project",
  "input": {
    "type": "orderby",
    "input": {
      "type": "extend",
      "input": {
        "type": "group",
        "input": {
          "type": "extend",
          "input": {
            "type": "bgp",
            "patterns": [
              {
                "type": "pattern",
                "termType": "Quad",
                "subject": {
                  "termType": "Variable",
                  "value": "S"
                },
                "predicate": {
                  "termType": "NamedNode",
                  "value": "http://www.example.org/p"
                },
                "object": {
                  "termType": "Variable",
                  "value": "O1"
                },
                "graph": {
                  "termType": "DefaultGraph",
                  "value": ""
                }
              },
              {
                "type": "pattern",
                "termType": "Quad",
                "subject": {
                  "termType": "Variable",
                  "value": "S"
                },
                "predicate": {
                  "termType": "NamedNode",
                  "value": "http://www.example.org/q"
                },
                "object": {
                  "termType": "Variable",
                  "value": "O2"
                },
                "graph": {
                  "termType": "DefaultGraph",
                  "value": ""
                }
              }
            ]
          },
          "variable": {
            "termType": "Variable",
            "value": "O12"
          },
          "expression": {
            "type": "expression",
            "subType": "operator",
            "operator": "+",
            "args": [
              {
                "type": "expression",
                "subType": "term",
                "term": {
                  "termType": "Variable",
                  "value": "O1"
                }
              },
              {
                "type": "expression",
                "subType": "term",
                "term": {
                  "termType": "Variable",
                  "value": "O2"
                }
              }
            ]
          }
        },
        "variables": [
          {
            "termType": "Variable",
            "value": "O12"
          }
        ],
        "aggregates": [
          {
            "type": "expression",
            "subType": "aggregate",
            "aggregator": "count",
            "expression": {
              "type": "expression",
              "subType": "term",
              "term": {
                "termType": "Variable",
                "value": "O1"
              }
            },
            "distinct": false,
            "variable": {
              "termType": "Variable",
              "value": "var0"
            }
          }
        ]
      },
      "variable": {
        "termType": "Variable",
        "value": "C"
      },
      "expression": {
        "type": "expression",
        "subType": "term",
        "term": {
          "termType": "Variable",
          "value": "var0"
        }
      }
    },
    "expressions": [
      {
        "type": "expression",
        "subType": "term",
        "term": {
          "termType": "Variable",
          "value": "O12"
        }
      }
    ]
  },
  "variables": [
    {
      "termType": "Variable",
      "value": "O12"
    },
    {
      "termType": "Variable",
      "value": "C"
    }
  ]
}