public function getAvatarThumb($size = 25, $options = null)
    {
        if (is_string($options)) {
            $options = ['default' => $options];
        }
        elseif (!is_array($options)) {
            $options = [];
        }

        // Default is "mm" (Mystery man)
        $default = array_get($options, 'default', 'mm');

        if ($this->avatar) {
            return $this->avatar->getThumb($size, $size, $options);
        }
        else {
            return '//www.gravatar.com/avatar/'.
                md5(strtolower(trim($this->email))).
                '?s='.$size.
                '&d='.urlencode($default);
        }
    }