def sagittaArcOrLine(self, endPoint, sag):
    """
    CadQuery plugin that creates an arc that can also be a straight line, unlike with the CadQuery 
    core Workplane.sagittaArc().

    :param endPoint: End point for the arc. A 2-tuple, in workplane coordinates.
    :param sag: Sagitta of the arc, or zero to get a straight line. A float, indicating the 
        perpendicular distance from arc center to arc baseline.
    """
    if sag == 0:
        return self.lineTo(endPoint[0], endPoint[1])
    else:
        return self.sagittaArc(endPoint, sag)