what parameters to be passes to beginInsertRows() when implementing tree

[DURGAPRASAD NEELAM]

I have a doubt with canFetch() and fetchMore() functions. i am implementing tree structure, when i scroll till the end canfetch() will be call and if returns true fetchMore() will be called where we have to fetch the data and insert items into tree.

void model::fetchMore(const QModelIndex& f_parent)
{
    //fetch the data needed and create items
    beginInsertRows(f_parent, row, lastRow);
    endInsertRows();
}

void model::fetchMore(const QModelIndex& f_parent)
{
    //fetch the data needed and create items
    beginInsertRows(f_parent, row, lastRow);
    endInsertRows();
}

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Please let me know In beginInsertRows, what parameters exactly we need to specify, It is confusing me..

I have fetched some data now, where I have 5 child's (previous data has remaining 5 child's) and followed by 10 parents and each parent has 10 child's. (f_parent parent has 5 childs already)

Now I need to insert 5 more children followed by 10 parents.

please let me know, what parameters I need to specify in beginInsertRows() exactly.

beginInsertRows(f_parent,5,f_parent.row()+10); ?
beginInsertRows(f_parent,f_parent.row(),f_parent.r ow()+10); ?
beginInsertRows(f_parent,5,10); ?

Documentation explained more in terms of list only(per this particular function) rather than tree.