- return ([l, l2] + lines([l[0], l2[0], l2[1], l[1]], 2)
- + lines([corners[0], l2[0], l2[1], corners[3]], 2)
- + lines([l[0], corners[1], corners[2], l[1]], 2))
+ return ([l, l2] + _lines([l[0], l2[0], l2[1], l[1]], 2)
+ + _lines([corners[0], l2[0], l2[1], corners[3]], 2)
+ + _lines([l[0], corners[1], corners[2], l[1]], 2))