Module StepByStep {
      Function CombinationsStep (a, nn) {
            c1=lambda (&f, &a) ->{
                  =car(a) : a=cdr(a) : f=len(a)=0
            }
            m=len(a)
            c=c1
            n=m-nn+1
            p=2
            while m>n {
                  c1=lambda c2=c,n=p, z=(,) (&f, &m) ->{
                        if len(z)=0 then z=cdr(m)
                        =cons(car(m),c2(&f, &z))
                        if f then z=(,) : m=cdr(m) : f=len(m)+len(z)<n
                   }
                  c=c1
                  p++
                  m--
            }
            =lambda c, a (&f) -> {
                  =c(&f, &a)
            }
      }
      k=false
      StepA=CombinationsStep((1, 2, 3, 4,5), 3)
      while not k {
                 Print StepA(&k)
      }
      k=false
      StepA=CombinationsStep((0, 1, 2, 3, 4), 3)
      while not k {
                 Print StepA(&k)
      }
      k=false
      StepA=CombinationsStep(("A", "B", "C", "D","E"), 3)
      while not k {
                 Print StepA(&k)
      }
      k=false
      StepA=CombinationsStep(("CAT", "DOG", "BAT"), 2)
      while not k {
                 Print StepA(&k)
      }
}
StepByStep