code: def _transformBy(self, matrix, **kwargs):
          
          for contour in self.contours:
              contour.transformBy(matrix)
          for component in self.components:
              component.transformBy(matrix)
          for anchor in self.anchors:
              anchor.transformBy(matrix)
          for guideline in self.guidelines:
              guideline.transformBy(matrix)
docs: Subclasses may override this method.