Append To A Vec In A BTreeMap In Rust

use std::collections::BTreeMap;

fn main() {
  let mut btm: BTreeMap<String, Vec<String>> = BTreeMap::new();
  btm.insert("alfa".to_string(), vec!["bravo".to_string()]);
  if let Some(update) = btm.get_mut("alfa") {
    update.push("charlie".to_string());
  }
  dbg!(btm);
}