if( !value.isValid() ) this->tags_.erase( key );
if( tags_.find( key ) != tags_.end() ) { if( !value.isValid() ) this->tags_.erase( tags_.find( key ) ); else tags_.find( key )->second = value; }
	void		set( QString key, cVariant value ) 	{		if( !value.isValid() )			this->tags_.erase( key );		else			this->tags_.insert(std::make_pair(key, value)); 	}