function setLogin($bool) { if ($bool) { $_SESSION['logged_in'] = true; } else { $_SESSION['logged_in'] = false; } }In this example, the function takes a boolean value as a parameter, which indicates whether the user is logged in or not. If the value is true, it sets the session variable 'logged_in' to true, otherwise, it sets it to false. This function could be part of a larger authentication package or library, which includes functions for logging in, creating accounts, and managing user sessions. Some popular authentication libraries for PHP include Laravel's built-in authentication system and the PHP Authentication Library.