You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: limestone_cavern.rs
    path of file: ./repos/rustrogueliketutorial/chapter-60-caverns3/src/map_builders
    
    the code of the file until where you have to start completion: use super::{BuilderChain, DrunkardsWalkBuilder, XStart, YStart, AreaStartingPosition,
    CullUnreachable, VoronoiSpawning, MetaMapBuilder, BuilderMap, TileType, DistantExit,
    DLABuilder, PrefabBuilder, CellularAutomataBuilder, AreaEndingPosition,
    BspDungeonBuilder, RoomSorter, RoomSort, NearestCorridors, RoomExploder, RoomDrawer,
    RoomBasedSpawner, XEnd, YEnd};
use rltk::RandomNumberGenerator;

pub fn limestone_cavern_builder(new_depth: i32, _rng: &mut rltk::RandomNumberGenerator, width: i32, height: i32) -> BuilderChain {
    let mut chain = BuilderChain::new(new_depth, width, height, "Limestone Caverns");
    chain.start_with(DrunkardsWalkBuilder::winding_passages());
    chain.with(AreaStartingPosition::new(XStart::CENTER, YStart::CENTER));
    chain.with(CullUnreachable::new());
    chain.with(AreaStartingPosition::new(XStart::LEFT, YStart::CENTER));
    chain.with(VoronoiSpawning::new());
    chain.with(Dis
    
    fn build(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        build_data.map.depth = 5;
        build_data.take_snapshot();

        // Build a BSP-based dungeon
        let mut builder = BuilderChain::new(5, build_data.width, build_data.height, "New Map");
        builder.start_with(BspDungeonBuilder::new());
        builder.with(RoomDrawer::new());
        builder.with(RoomSorter::new(RoomSort::RIGHTMOST));
        builder.with(NearestCorridors::new());
        builder.with(RoomExploder::new());
        builder.with(RoomBasedSpawner::new());
        builder.build_map(rng);

        // Add the history to our history
        for h in builder.build_data.history.iter() {
            build_data.history.push(h.clone());
        }
        build_data.take_snapshot();

        // Copy the right half of the BSP map into our map
        for x in build_data.map.width / 2 .. build_data.map.width {
            for y in 0 .. build_data.map.height {
                let idx = build_data.map.xy_idx(x, y);
                build_data.map.tiles[idx] = builder.build_data.map.tiles[idx];
            }
        }
        build_data.take_snapshot();

        // Keep Voronoi spawn data from the left half of the map
        let w = build_data.map.width;
        build_data.spawn_list.retain(|s| {
            let x = s.0 as i32 / w;
            x < w / 2
        });

        // Keep room spawn data from the right half of the map
        for s in builder.build_data.spawn_list.iter() {
            let x = s.0 as i32 / w;
            if x > w / 2 {
                build_data.spawn_list.push(s.clone());
            }
        }
    }