code: def iter_values(self):
          
          yVal = self._element.yVal
          if yVal is None:
              return
  
          for idx in range(yVal.ptCount_val):
              yield yVal.pt_v(idx)
docs: 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).