Usage
There are three ways to load authentication credentials for google services.
// 1. load credentials from an environment variable
let authentication = from_environment_variable;
// 2. load credentials from a file path
let authentication = from_file;
// 3. load credentials from your machine's environment using well known locations
let authentication = from_env.authentication;
let Some = authentication else ;
// log out the authentication details
debug!;
// load project id from user input or from the service account file
let project_id = authentication.project_id.expect;
// create the bearer token
let token = authentication.token?;