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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def update_evt_types(self):
 """Update the event types list when dialog is opened."""

        self.event_types = self.parent.notes.annot.event_types
        self.idx_evt_type.clear()
        self.frequency['norm_evt_type'].clear()
        for ev in self.event_types:
            self.idx_evt_type.addItem(ev)
            self.frequency['norm_evt_type'].addItem(ev)