{
  "csv": "week,attendance\nW1,8\nW1,10\nW2,\nW4,12\n",
  "roles": {
    "group": "week",
    "value": "attendance",
    "unit": "people"
  },
  "periods": [
    "W1",
    "W2",
    "W3",
    "W4"
  ],
  "charts": [
    {
      "grammar": "bar",
      "reducer": "sum",
      "annotations": [
        {
          "group": "W1",
          "text": "Opening event"
        }
      ]
    },
    {
      "grammar": "line",
      "reducer": "mean"
    }
  ]
}