Cannot assign through subscript: subscript is get-only after swift 4.1

[iNarendra]

When i try to Write data

let csv = try CSVParser(filePath: "path/to/csvfile")
// get every row in csv

    below line throws an error after updating to 4.1
csv[0] = ["test0", "test1", "test2"]  //  **Cannot assign through subscript: subscript is get-only**

csv.wirite(toFilePath: "path/to/destination/file")