{
  "uniqueFields": ["a", "foo[]", "bar[][]", "z", "notes"],
  "headerFields": [
    "a",
    "foo[0]",
    "foo[1]",
    "foo[2]",
    "bar[0][0]",
    "bar[0][1]",
    "z",
    "notes"
  ],
  "preview": [
    ["a", "1", "2", "3", "", "", "z", "foo is an array of simple values"],
    ["a", "1", "", "", "", "", "z", "foo is not always of the same length"]
  ]
}