Method add

proof_system/src/statement/mod.rs:153–156

(&mut self, item: Statement<E>)

    }

    pub fn add(&mut self, item: Statement<E>) -> usize {
        self.0.push(item);
        self.0.len() - 1
    }

    pub fn is_empty(&self) -> bool {
        self.0.is_empty()