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: session.rs
    path of file: ./repos/goose/examples
    
    the code of the file until where you have to start completion: //! Goose load test example, leveraging the per-GooseUser `GooseUserData` field
// to store a per-user session JWT authentication token.
//!
//! ## License
//!
//! Copyright 2020-2022 Jeremy Andrews
//!
//! Licensed under the Apache License, Version 2.0 (the "License");
//! you may not use this file except in compliance with the License.
//! You may obtain a copy of the License at
//!
//! <http://www.apache.org/l
    
async fn website_signup(user: &mut GooseUser) -> TransactionResult {
    let params = [("username", "test_user"), ("password", "")];
    let response = match user.post_form("/signup", &params).await?.response {
        Ok(r) => match r.json::<AuthenticationResponse>().await {
            Ok(j) => j,
            Err(e) => return Err(Box::new(e.into())),
        },
        Err(e) => return Err(Box::new(e.into())),
    };

    user.set_session_data(Session {
        jwt_token: response.jwt_token,
    });

    Ok(())
}