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: fd_append.rs
    path of file: ./repos/wasmer/tests/wasi-wast/wasi/tests
    
    the code of the file until where you have to start completion: // WASI:
// tempdir: .

use std::fs::OpenOptions;
use std::io::{Read, Write};
use std::path::PathBuf;

static STR1: &str = "Hello, world!\n";
static STR2: &str = "Goodbye, world!\n";

fn main() {
    let file = {
        #[cfg(not(target_os = "wasi"))]
    
fn main() {
    let file = {
        #[cfg(not(target_os = "wasi"))]
        let mut base = PathBuf::from("test_fs/temp");
        #[cfg(target_os = "wasi")]
        let mut base = PathBuf::from(".");

        base.push("fd_append_test");
        base
    };

    {
        let mut file_handle = OpenOptions::new()
            .create_new(true)
            .append(true)
            .open(&file)
            .expect("Couldn't create file");
        file_handle.write_all(STR1.as_bytes()).unwrap();
        file_handle.flush().unwrap();
        file_handle.sync_all();
    }
    {
        let mut file_handle = OpenOptions::new()
            .append(true)
            .open(&file)
            .expect("Couldn't reopen file to append");
        file_handle.write_all(STR2.as_bytes()).unwrap();
        file_handle.flush().unwrap();
        file_handle.sync_all();
    }

    {
        let mut file_handle = OpenOptions::new()
            .read(true)
            .open(&file)
            .expect("Couldn't reopen file to read");

        let mut test = String::new();
        file_handle.read_to_string(&mut test);

        assert_eq!(&test, &format!("{}{}", STR1, STR2));
        println!("{:?}", &test);
    }
    std::fs::remove_file(&file).unwrap();
}