) -> Result<(), Box<dyn Error>> {
for (index, c) in columns.iter().enumerate() {
let tail = if index == columns.len() - 1 { "\n" } else { "\t" };
) -> Result<(), Box<dyn Error>> {
for (index, c) in columns.iter().enumerate() {
let tail = if index == columns.len() - 1 { "\n" } else { "\t" };