add-one 1.0.0

Adds one to a number
Documentation 
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extern crate add_one;

use add_one::add_one;
use std::env;
use std::io::stdout;
use std::process::exit;

fn main() {
    let mut args = env::args();

    if args.next().is_none() {
        eprintln!("Too few arguments. Expected program name and a single argument.");
        return;
    };

    let input_str = if let Some(arg) = args.next() {
        arg
    } else {
        eprintln!("Too few arguments. Expected a single argument.");
        return;
    };

    if args.next().is_some() {
        eprintln!("Too many arguments. Expected a single argument.");
        return;
    };

    match add_one(input_str.as_bytes(), &mut stdout()) {
        Ok(()) => println!(),
        Err(e) => {
            eprintln!("Error: {}", e);
            exit(1);
        }
    }
}