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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 tab_navigate(self, delta=1):

 """Ctrl+Tab"""

        if delta > 0 and self.currentIndex() == self.count()-1:
            index = delta-1
        elif delta < 0 and self.currentIndex() == 0:
            index = self.count()+delta
        else:
            index = self.currentIndex()+delta
        self.setCurrentIndex(index)