function exclude(array $exclusionFields = [], $exclusionBehave = self::EXCLUDE_DISALLOW)
    {
        $exclude = [];
        foreach ($this->value as $field => $term)
        {
            if (!empty($exclusionFields))
            {
                $flag = in_array($field, $exclusionFields);

                ($exclusionBehave != self::EXCLUDE_ALLOW) ?: $flag = !$flag;

                if ($flag)
                    // The Field not considered as Expression Term
                    continue;
            }

            $exclude[$field] = $term;

        }// end foreach


        return new StdArray($exclude);
    }