Generate each float Y value in this series, in the order they appear
        on the chart. A value of `None` represents a missing Y value
        (corresponding to a blank Excel cell).

def iter_values(self):
        """
        Generate each float Y value in this series, in the order they appear
        on the chart. A value of `None` represents a missing Y value
        (corresponding to a blank Excel cell).
        """
        yVal = self._element.yVal
        if yVal is None:
            return

        for idx in range(yVal.ptCount_val):
            yield yVal.pt_v(idx)