private fun unrail_paces: Array[Couple[Int, Int]] do
var ret = new Array[Couple[Int,Int]].with_capacity(self)
var extremes = new Couple[Int, Int]((self - 1) * 2, (self - 1) * 2)
private fun unrail_paces: Array[Couple[Int, Int]] do
var ret = new Array[Couple[Int,Int]].with_capacity(self)
var extremes = new Couple[Int, Int]((self - 1) * 2, (self - 1) * 2)