+ cor_d = sorted([(corners[0][0] * c[1] - c[0] * corners[0][1], c) for c in
+ corners[1:]])
+ corners = [corners[0]] + [c for _, c in cor_d]
+ return (_lines(corners, 0) + [(corners[0], corners[3]),
+ (corners[1], corners[2])],
+ _lines(corners[1:4] + [corners[0]], 0) +
+ [(corners[0], corners[1]), (corners[2], corners[3])])