Method is_empty

publication/code/chapter06/hashmap.rs:36–46

(&self)

    }

    fn is_empty(&self) -> bool {
        let mut empty = true;
        for &d in self.slot.iter() {
            if 0 != d  {
                empty = false;
                break;
            }
        }

        empty
    }

    fn clear(&mut self) {
        let mut slot = Vec::with_capacity(self.cap);