{
    "srce":"dcard",
    "sequence":1,
    "defn": [
        {
            "key": "{Description}",
            "map": "y",
            "flag": "g",
            "field": "f20",
            "regex": ".{1,20}",
            "retain": "y"
        }
    ],
    "name": "First 20",
    "where": [
        {}
    ],
    "function": "extract",
    "description": "pull first 20 characters from description for mapping"
}