Function instapaper::authenticate

pub fn authenticate(
    username: &str, 
    password: &str, 
    consumer_key: &str, 
    consumer_secret: &str
) -> Result<Client>

Must be called to obtain the oauth_key and oauth_secret. Once you have them, you don't need to call this every time you want to access the API. You can store the resulting client's attributes somewhere and instantiate it yourself without this method. See the module-level documentation for a complete example.