{
  "source_table": "ltc",
  "grouping_column": "id",
  "transformation_type": "time_since",
  "time_units": "years",
  "from_first": true,
  "output_feature_name": "years_with_asthma",
  "date_column": "asthma",
  "cutoff_date": "2021-03-25",
  "absent_default_value": 40
}
