Method insert

src/entity/sparse.rs:171–178

(&mut self, key: K, value: V)

    #[inline]
    #[track_caller]
    pub fn insert(&mut self, key: K, value: V) -> Option<V> {
        if let Some(entry) = self.get_mut(key) {
            Some(mem::replace(entry, value))
        } else {
            self.insert_unique(key, value);
            None
        }
    }

    /// Insert a value into the map without checking for an existing element.
    ///