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: json.rs
    path of file: ./repos/logos/examples
    
    the code of the file until where you have to start completion: //! JSON parser written in Rust, using Logos.
//!
//! If the file is a valid JSON value, it will be printed
//! to the terminal using the debug format.
//!
//! Otherwise, an error will be printed with its location.
//!
//! Usage:
//!     cargo run --example json <path/to/file>
//!
//! Example:
//!     cargo run --example json examples/example.json

/* ANCHOR: all */
use logos::{Lexer, Logos, Span};

use std::collections::HashMap;
use std::env;
use std::fs;

type Error = (String, Span);

type Result<T> = std::result::Result<T, Error>;

/* ANCHOR: tokens */
/// All meaningful JSON tokens.
///
/// > NOTE: regexes for [`Token::Number`] and [`Token::String`] may not
/// > catch all possible values, especially for strings. If 
    
fn main() {
    let filename = env::args().nth(1).expect("Expected file argument");
    let src = fs::read_to_string(&filename).expect("Failed to read file");

    let mut lexer = Token::lexer(src.as_str());

    match parse_value(&mut lexer) {
        Ok(value) => println!("{:#?}", value),
        Err((msg, span)) => {
            use ariadne::{ColorGenerator, Label, Report, ReportKind, Source};

            let mut colors = ColorGenerator::new();

            let a = colors.next();

            Report::build(ReportKind::Error, &filename, 12)
                .with_message("Invalid JSON".to_string())
                .with_label(
                    Label::new((&filename, span))
                        .with_message(msg)
                        .with_color(a),
                )
                .finish()
                .eprint((&filename, Source::from(src)))
                .unwrap();
        }
    }
}