docs: def setVerticalAxis(self, axis):
          """
          Sets the vertical axis for this chart.
          
          :param      axis | <XChartAxis>
          """
          self._verticalAxis = axis
          if axis:
              axis.setOrientation(Qt.Vertical)
              self.uiYAxisVIEW.setFixedWidth(axis.minimumLabelWidth() + 15)
          
          self.uiYAxisVIEW.setVisible(axis is not None)