Lifetime issue with bufwriter

sample.rs

extern crate ssh2;

use std::net::TcpStream;
use std::path::Path;
use std::io::BufWriter;

use ssh2::Session;
use ssh2::{OpenType, WRITE, TRUNCATE};


fn create_session<'a>() -> (TcpStream, Session, BufWriter<ssh2::File<'a>>) {
    let tcp = TcpStream::connect("test:22").expect("Cannot connect");
    let mut sess = Session::new().expect("cannot start session");
    sess.handshake(&tcp).expect("handshake failed");

    sess.userauth_password("test", "boo").expect("Cannot authenticate");
    assert!(sess.authenticated());

    let sftp = sess.sftp().expect("Cannot start sftp subsystem");
    sftp.create(Path::new("sample.txt")).expect("Cannot create file in target directory");
    let f = sftp.open_mode(Path::new("sample.txt"), WRITE | TRUNCATE, 0o644, OpenType::File).expect("Cannot open file file for writing");
    let mut buf_file = BufWriter::new(f);

    (tcp, sess, buf_file)
}

struct Sample<'b> {
//    session: Session,
//    sftp: ssh2::Sftp<'a>
    buf_file: BufWriter<ssh2::File<'b>>
}

impl <'b> Sample<'b> {
    fn new(buf_file: BufWriter<ssh2::File<'b>>) -> Sample<'b> {
        Sample {
//            session: s,
            buf_file
        }
    }

    fn print_some(&self) -> () {
        println!("Got it!!");
    }
}


fn main() {
    let (stream, sess, buf_file) = create_session();
    let s = Sample::new(buf_file);
    s.print_some();

}

extern crate ssh2;

use std::net::TcpStream;
use std::path::Path;
use std::io::BufWriter;
use std::io::Write;

use ssh2::Session;
use ssh2::{OpenType, WRITE, TRUNCATE};


fn create_session() -> (TcpStream, Session) {
    let tcp = TcpStream::connect("test:22").expect("Cannot connect");
    let mut sess = Session::new().expect("cannot start session");
    sess.handshake(&tcp).expect("handshake failed");

    sess.userauth_password("test", "boo").expect("Cannot authenticate");
    assert!(sess.authenticated());

    (tcp, sess)
}

struct Sample<'b> {
//    session: Session,
//    sftp: ssh2::Sftp<'a>
    buf_file: BufWriter<ssh2::File<'b>>
}

impl <'b> Sample<'b> {
    fn new(buf_file: BufWriter<ssh2::File<'b>>) -> Sample<'b> {
        Sample {
//            session: s,
            buf_file
        }
    }

    fn write_to_file(&mut self, contents: &[u8]) {
        self.buf_file.write_all(&contents).expect("Cannot write to file");
    }

    fn print_some(&self) -> () {
        println!("Got it!!");
    }
}


fn handle_file() {
    let (_stream, sess) = create_session();
    let sftp = sess.sftp().expect("Cannot start sftp subsystem");

    sftp.create(Path::new("sample.txt")).expect("Cannot create file in target directory");
    let f = sftp.open_mode(Path::new("sample.txt"), WRITE | TRUNCATE, 0o644, OpenType::File).expect("Cannot open file file for writing");
    let buf_file = BufWriter::new(f);

    let mut s = Sample::new(buf_file);
    s.print_some();
    s.write_to_file("Nooooo ".as_bytes());
    s.write_to_file("but yesssssssss".as_bytes());
}



fn main() {
    handle_file()
}