pub trait LeafDownloadTask: DownloadTask + Display {
// Required methods
fn clone_as_leaf_task(&self) -> Box<dyn LeafDownloadTask>;
fn abs_group_path(&self) -> Option<String>;
fn context(&self) -> &dyn DownloadContext;
fn finish(&self);
// Provided method
fn priority(&self) -> DownloadTaskPriority { ... }
}