defender::verify_number PHP Method

    protected function verify_number()
    {
        if ($this->field_config['required'] && empty($this->field_value)) {
            self::setInputError($this->field_name);
        }
        if (is_array($this->field_value)) {
            $vars = array();
            foreach ($this->field_value as $val) {
                if (!empty($val) && isnum($val, TRUE)) {
                    $vars[] = $val;
                }
            }
            $delimiter = !empty($this->field_config['delimiter']) ? $this->field_config['delimiter'] : ",";
            $value = implode($delimiter, $vars);
            return $value;
            // empty str is returned if $vars ends up empty
        } elseif (empty($this->field_value) || isnum($this->field_value, TRUE)) {
            return $this->field_value;
        } else {
            return FALSE;
        }
    }