{
    head:{
        type:"APACHE_DRILL_PHYSICAL",
        version:"1",
        generator:{
            type:"manual"
        }
    },
        graph:[
        {
            @id:1,
            pop:"mock-sub-scan",
            url: "http://apache.org",
            entries:[
                {records: 1, types: [
                  {name: "red", type: "INT", mode: "REQUIRED"}
                ]}
            ]
        }, {
           @id:2,
           child: 1,
           pop:"project",
           exprs: [
             { ref: "col1", expr:"red" }
           ]
           }, {
          pop : "trace",
          @id : 3,
          child : 2,
          tag : "mock-scan"
          }, {
            @id: 4,
            child: 3,
            pop: "screen"
        }
    ]
}