Code shared from the Rust Playground

playground.rs

use std::rc::Rc;

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

impl ResultSet {
    fn pop(&mut self) -> Option<Row> {
        self.rows.pop().map(|columns| Row {
            column_names: self.column_names.clone(),
            columns: columns,
        })
    }
}

struct Rows {
    result_set: ResultSet,
}

struct Row {
    column_names: Rc<Vec<String>>,
    columns: Vec<i32>,
}

impl Iterator for Rows {
    type Item = Row;
    
    fn next(&mut self) -> Option<Row> {
        self.result_set.pop()
    }
}

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