code: def _interpolate(self, factor, minInfo, maxInfo, round=True, suppressError=True):
          
          minInfo = minInfo._toMathInfo()
          maxInfo = maxInfo._toMathInfo()
          result = interpolate(minInfo, maxInfo, factor)
          if result is None and not suppressError:
              raise FontPartsError(("Info from font '%s' and font '%s' could not be "
                                    "interpolated.")
                                   % (minInfo.font.name, maxInfo.font.name))
          if round:
              result = result.round()
          self._fromMathInfo(result)
docs: Subclasses may override this method.