How to remove the dot line in QTreeWidget?

[cspp]

I use the QTreeWidgt like this:

QTreeWidget* pShowListView = new QTreeWidget;
QTreeWidgetItem* item = NULL;
QTreeWidgetItem* preItem = NULL;
for( ...; ...; ....)
{
     item = new QTreeWidgetItem(pShowListView,preItem);
     //init the item value
 
    preItem = item;
}

QTreeWidget* pShowListView = new QTreeWidget;
QTreeWidgetItem* item = NULL;
QTreeWidgetItem* preItem = NULL;
for( ...; ...; ....)
{
     item = new QTreeWidgetItem(pShowListView,preItem);
     //init the item value

    preItem = item;
}

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then how can I remove the line in my Treewidget?
the line like this:

|__My Record A
|__My Record B
|__My Record C
|__My Record D