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: constraints.rs
    path of file: ./repos/rustrogueliketutorial/chapter-66-spells/src/map_builders/waveform_collapse
    
    the code of the file until where you have to start completion: use super::{TileType, Map, MapChunk, tile_idx_in_chunk};
use std::collections::HashSet;

pub fn build_patterns(map : &Map, chunk_size: i32, include_flipping: bool, dedupe: bool) -> Vec<Vec<TileType>> {
    let chunks_x = map.width / chunk_size;
    let chunks_y = map.height / chunk_size;
    let mut patterns = Vec::new();

    for cy in 0..chunks_y {
        for cx in 0..chunks_x {
            // Normal orientation
            let mut pattern : Vec<TileType> = Vec::new();
            let start_x = cx * chunk_size;
            let end_x = (cx+1) * chunk_size;
            let start_y = cy * chunk_size;
            let end_y = (cy+1) * chunk_size;

            for y in start_y .. end_y {
         
    
pub fn render_pattern_to_map(map : &mut Map, chunk: &MapChunk, chunk_size: i32, start_x : i32, start_y: i32) {
    let mut i = 0usize;
    for tile_y in 0..chunk_size {
        for tile_x in 0..chunk_size {
            let map_idx = map.xy_idx(start_x + tile_x, start_y + tile_y);
            map.tiles[map_idx] = chunk.pattern[i];
            map.visible_tiles[map_idx] = true;
            i += 1;
        }
    }

    for (x,northbound) in chunk.exits[0].iter().enumerate() {
        if *northbound {
            let map_idx = map.xy_idx(start_x + x as i32, start_y);
            map.tiles[map_idx] = TileType::DownStairs;
        }
    }
    for (x,southbound) in chunk.exits[1].iter().enumerate() {
        if *southbound {
            let map_idx = map.xy_idx(start_x + x as i32, start_y + chunk_size -1);
            map.tiles[map_idx] = TileType::DownStairs;
        }
    }
    for (x,westbound) in chunk.exits[2].iter().enumerate() {
        if *westbound {
            let map_idx = map.xy_idx(start_x, start_y + x as i32);
            map.tiles[map_idx] = TileType::DownStairs;
        }
    }
    for (x,eastbound) in chunk.exits[3].iter().enumerate() {
        if *eastbound {
            let map_idx = map.xy_idx(start_x + chunk_size - 1, start_y + x as i32);
            map.tiles[map_idx] = TileType::DownStairs;
        }
    }
}