code: def vary_by_categories(self):
          
          varyColors = self._element.varyColors
          if varyColors is None:
              return True
          return varyColors.val
docs: Read/write boolean value specifying whether to use a different color
          for each of the points in this plot. Only effective when there is
          a single series; PowerPoint automatically varies color by series when
          more than one series is present.