Method insert

src/common/max_heap.rs:57–61

(&mut self, key: K)

    }

    pub fn insert(&mut self, key: K) {
        let i = self.keys.len();
        self.keys.push(key);
        heap_fix(&mut self.keys, i);
    }

    //for test
    pub fn keys_slice(&self) -> &[K] {