{
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                0.25
            ], 
            "parents": [
                "Difficulty", 
                "Intelligence"
            ], 
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            "children": [
                "Letter"
            ]
        }, 
        "Intelligence": {
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            "mean_scal": [], 
            "parents": null, 
            "variance": 18, 
            "type": "lg", 
            "children": [
                "SAT", 
                "Grade"
            ]
        }, 
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            "mean_scal": [], 
            "parents": null, 
            "variance": 18, 
            "type": "lg", 
            "children": [
                "Grade"
            ]
        }, 
        "Letter": {
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            "mean_scal": [
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            ], 
            "parents": [
                "Grade"
            ], 
            "variance": 10, 
            "type": "lg", 
            "children": null
        }, 
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            "mean_scal": [
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            ], 
            "parents": [
                "Intelligence"
            ], 
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            "type": "lg", 
            "children": null
        }
    }
}