def makeCounterClockwise(self, ips):
    """
    Re-order nodes to ensure positive area (in-place operation)
    """
    area = self.getArea(ips[0], ips[1], ips[2])
    if area < -self.EPS:
      ip1, ip2 = ips[1], ips[2]
      # swap
      ips[1], ips[2] = ip2, ip1

    Re-order nodes to ensure positive area (in-place operation)
    
recipes/Python/579021_Delaunay_triangulation/recipe-579021.py