This must return an iterator that returns wrapped contours.

        Subclasses may override this method.

def _iterContours(self, **kwargs):
        """
        This must return an iterator that returns wrapped contours.

        Subclasses may override this method.
        """
        count = len(self)
        index = 0
        while count:
            yield self[index]
            count -= 1
            index += 1