Subclasses may override this method.

def _insertBPoint(self, index, type, anchor, bcpIn, bcpOut, **kwargs):
        """
        Subclasses may override this method.
        """
        # insert a simple line segment at the given anchor
        # look it up as a bPoint and change the bcpIn and bcpOut there
        # this avoids code duplication
        self._insertSegment(index=index, type="line",
                            points=[anchor], smooth=False)
        bPoints = self.bPoints
        index += 1
        if index >= len(bPoints):
            # its an append instead of an insert
            # so take the last bPoint
            index = -1
        bPoint = bPoints[index]
        bPoint.bcpIn = bcpIn
        bPoint.bcpOut = bcpOut
        bPoint.type = type