Adldap\Auth\Guard::attempt PHP Method

    public function attempt($username, $password, $bindAsUser = false)
    {
        $this->validateCredentials($username, $password);
        try {
            $this->bind($username, $password);
        } catch (BindException $e) {
            // We'll catch the BindException here to return false
            // to allow developers to use a simple if / else
            // using the authenticate method.
            return false;
        }
        // If we're not allowed to bind as the user,
        // we'll rebind as administrator.
        if ($bindAsUser === false) {
            // We won't catch any BindException here so
            // developers can catch rebind failures.
            $this->bindAsAdministrator();
        }
        // No bind exceptions, authentication passed.
        return true;
    }