pub trait MappedTrait<K, V>: Sync + Send{
// Required methods
fn for_each(&self, action: &dyn Fn(K, V));
fn get(&self, key: K) -> Result<V>;
fn get_or(&self, key: K, fallback: V) -> V;
fn has(&self, key: K) -> bool;
fn keys(&self) -> Listed<K>;
fn len(&self) -> i32;
fn to_list(&self) -> List<(K, V)>;
fn to_map(&self) -> Map<K, V>;
fn to_map_builder(&self) -> MapBuilder<K, V>;
fn values(&self) -> Listed<V>;
}