Code shared from the Rust Playground

playground.rs

struct ResultSet {
    column_names: Vec<String>,
    rows: Vec<Vec<i32>>,
}

impl ResultSet {
    fn get<'rs>(&'rs self, row_no: usize) -> Option<Row<'rs>> {
        self.rows.get(row_no).map(|columns| Row {
            column_names: self.column_names.as_slice(),
            columns: columns.as_slice(),
        })
    }
}

struct Rows<'rs> {
    result_set: &'rs ResultSet,
    row_no: usize,
}

struct Row<'rs> {
    column_names: &'rs[String],
    columns: &'rs[i32],
}

impl<'rs> Iterator for Rows<'rs> {
    type Item = Row<'rs>;
    
    fn next(&mut self) -> Option<Row<'rs>> {
        let r = self.result_set.get(self.row_no);
        self.row_no += 1;
        r
    }
}

fn main() {
    println!("{}", 4.0f64.powf(1.0/3.0))
}