pub trait MessageSessionRelayProtocol {
fn find_prev(&self) -> Option<Did>;
fn push_prev(&mut self, current: Did, prev: Did);
fn next_hop(&mut self, current: Did, next: Did);
fn add_to_path(&mut self, node: Did);
fn add_from_path(&mut self, node: Did);
fn remove_to_path(&mut self) -> Option<Did>;
fn remove_from_path(&mut self) -> Option<Did>;
}