{
  "type": "from",
  "input": {
    "type": "project",
    "input": {
      "type": "join",
      "input": [
        {
          "type": "bgp",
          "patterns": [
            {
              "type": "pattern",
              "termType": "Quad",
              "subject": {
                "termType": "Variable",
                "value": "g"
              },
              "predicate": {
                "termType": "NamedNode",
                "value": "http://purl.org/dc/elements/1.1/publisher"
              },
              "object": {
                "termType": "Variable",
                "value": "who"
              },
              "graph": {
                "termType": "DefaultGraph",
                "value": ""
              }
            }
          ]
        },
        {
          "type": "graph",
          "input": {
            "type": "bgp",
            "patterns": [
              {
                "type": "pattern",
                "termType": "Quad",
                "subject": {
                  "termType": "Variable",
                  "value": "x"
                },
                "predicate": {
                  "termType": "NamedNode",
                  "value": "http://xmlns.com/foaf/0.1/mbox"
                },
                "object": {
                  "termType": "Variable",
                  "value": "mbox"
                },
                "graph": {
                  "termType": "DefaultGraph",
                  "value": ""
                }
              }
            ]
          },
          "name": {
            "termType": "Variable",
            "value": "g"
          }
        }
      ]
    },
    "variables": [
      {
        "termType": "Variable",
        "value": "who"
      },
      {
        "termType": "Variable",
        "value": "g"
      },
      {
        "termType": "Variable",
        "value": "mbox"
      }
    ]
  },
  "default": [
    {
      "termType": "NamedNode",
      "value": "http://example.org/dft.ttl"
    }
  ],
  "named": [
    {
      "termType": "NamedNode",
      "value": "http://example.org/alice"
    },
    {
      "termType": "NamedNode",
      "value": "http://example.org/bob"
    }
  ]
}