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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 mousePressEvent(self, event):
 """Jump to window when user clicks on overview. Parameters event : instance of QtCore.QEvent it contains the position that was clicked. """

        if self.scene is not None:
            x_in_scene = self.mapToScene(event.pos()).x()
            window_length = self.parent.value('window_length')
            window_start = int(floor(x_in_scene / window_length) *
                               window_length)
            if self.parent.notes.annot is not None:
                window_start = self.parent.notes.annot.get_epoch_start(
                        window_start)
            self.update_position(window_start)