use itertools: permutations
use math.cf: fac
use sys: exit

function error(s)
   print("Error: generators test ", s, " failed.")
   exit(1)
end

begin
   for n in 0..6
      a = cf.permutations(list(0..n-1))
      b = permutations(list(0..n-1)).list()
      if a!=b or len(a)!=fac(n)
         error("#1")
      end
   end
end