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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 keyPressEvent(self, evt):

 """This handles Ctrl+PageUp, Ctrl+PageDown, Ctrl+Tab, Ctrl+Shift+Tab"""

        incr = 0
        if evt.modifiers() == Qt.ControlModifier:
            n = self.tabWidget.count()
            if evt.key() in [Qt.Key_PageUp, Qt.Key_Backtab]:
                incr = -1
            elif evt.key() in [Qt.Key_PageDown, Qt.Key_Tab]:
                incr = 1
            if incr != 0:
                new_index = self._get_tab_index() + incr
                if new_index < 0:
                    new_index = n - 1
                elif new_index >= n:
                    new_index = 0
                self.tabWidget.setCurrentIndex(new_index)