রাস্ট extend

fn main() {
  use std::collections::HashMap;

  let mut user = HashMap::new();
  user.insert("নাম", "মোঃ আরিফ");
  user.insert("দেশ", "বাংলাদেশ");

  let info = HashMap::from([
    ("শহর", "ঢাকা")
  ]);

  user.extend(info);

  println!("{:?}", user);
}