code: def horz_offset(self):
          
          x, xMode = self.x, self.xMode
          if x is None or xMode is None or xMode.val != ST_LayoutMode.FACTOR:
              return 0.0
          return x.val
docs: The float value in ./c:x@val when ./c:xMode@val == "factor". 0.0 when
          ./c:x is not present or ./c:xMode@val != "factor".