protected function getVersionsToCompare(): string
    {
        return escapeshellarg($this->from) . (empty($this->to) ? '' : ' ' . escapeshellarg($this->to));
    }
protected function getVersionsToCompare(): string
    {
        return escapeshellarg($this->from) . (empty($this->to) ? '' : ' ' . escapeshellarg($this->to));
    }
protected function getVersionsToCompare ( ) : string { return escapeshellarg ( $ this -> from ) . ( empty ( $ this -> to ) ? '' : ' ' . escapeshellarg ( $ this -> to ) ) ; }
Return the from commit id to diff

@return string
Return the from commit id to diff