code: def _clear(self, contours=True, components=True, anchors=True,
                 guidelines=True, image=True):
          
          if contours:
              self.clearContours()
          if components:
              self.clearComponents()
          if anchors:
              self.clearAnchors()
          if guidelines:
              self.clearGuidelines()
          if image:
              self.clearImage()
docs: Subclasses may override this method.