Subclasses may override this method.

def _transformBy(self, matrix, **kwargs):
        """
        Subclasses may override this method.
        """
        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)