[PyQt] hierarchical model for QTreeView

[Doug Luce]

Outside of QDirModel, I'd like to confirm (or, even better, be told I'm 
wrong) that the only way to use a hierarchical tree model under QTreeView 
is by making a custom one as a class.

That is to say, there's not some existing Qt class that allows one to 
build a directory-like model for QTreeView directly.

In my application, a QTreeView is to be populated with a list of client 
names; once a name is clicked on, a sub-level is to be populated with a 
list of attributes and displayed.  This is different from a QDirModel, 
which is built specifically for file system hierarchy, and populated all 
at once.

Thanks,

Doug