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: canvas_subframe.rs
    path of file: ./repos/ggez/examples
    
    the code of the file until where you have to start completion: //! An example of how to use an `InstanceArray` with a `Canvas`.
//!
//! You really want to run this one in release mode.

use ggez::event;
use ggez::graphics::{self, Color};
use ggez::{Context, GameResult};
    
pub fn main() -> GameResult {
    if cfg!(debug_assertions) && env::var("yes_i_really_want_debug_mode").is_err() {
        eprintln!(
            "Note: Release mode will improve performance greatly.\n    \
             e.g. use `cargo run --example canvas_subframe --release`"
        );
    }
    let resource_dir = if let Ok(manifest_dir) = env::var("CARGO_MANIFEST_DIR") {
        let mut path = path::PathBuf::from(manifest_dir);
        path.push("resources");
        path
    } else {
        path::PathBuf::from("./resources")
    };

    let cb = ggez::ContextBuilder::new("canvas_subframe", "ggez").add_resource_path(resource_dir);

    let (mut ctx, events_loop) = cb.build()?;
    let state = MainState::new(&mut ctx);
    event::run(ctx, events_loop, state)
}