Definition of 'apply' of MDI GUI

[anson]

Dear people,

   I don't understand EXACTLY how apply works in MDI GUIS? What's the purpose of it?

def __init__(self, parent, doc, *args):
        apply(QWidget.__init__,(self, parent) + args)
        self.doc = doc
        self.connect(self.doc, PYSIGNAL("sigDocModified"),
                     self.slotDocModified)
        self.connect(self.doc, PYSIGNAL("sigDocTitleChanged"),
                     self.setCaption)
        # Set initial values
        self.slotDocModified(self.doc.modified())

I don't quite understand, what's the purpose of apply.

Anson