def urbanmain() = {

  import M5b._

  //println(optimise(load_bff("benchmark.bf")).length)
  //println(optimise(load_bff("mandelbrot.bf")).length)

  val urban_l1 = optimise(load_bff("benchmark.bf")).length
  val urban_l2 = optimise(load_bff("mandelbrot.bf")).length 

  assert(urban_l1 == 181)
  assert(urban_l2 == 11203)
}