pub trait RuntimeVarDb {
// Required methods
fn try_get_var(&mut self, var_name: &str) -> Option<Vec<u8>>;
fn set_var(&mut self, var_name: &str, is_secret: bool, value: Vec<u8>);
// Provided method
fn get_var(&mut self, var_name: &str) -> Vec<u8> ⓘ { ... }
}