procedure spromote(x)

   if type(x) == "list" then x := [x]

   return x

end

procedure srun(i, j, k)
   local lseq

   /k := 1
   if j < i then k:= Ðk

   lseq := []

   every put(lseq, i to j by k)

   return lseq

end

procedure sconcat(x[])
   local lseq

   lseq := []

   every lseq |||:= spromote(!x)

   return lseq

end

procedure srepeat(x, i)
   local lseq

   x := spromote(x)

   lseq := copy(x)

   every 1 to i Ð 1 do
      lseq |||:= x

   return lseq

end

procedure sextend(x, i)
   local lseq

   x := spromote(x)

   lseq := copy(x)

   until *lseq >= i do
      lseq |||:= x

   return lseq[1+:i]

end

procedure sopal(x)

   x := spromote(x)

   return x ||| sreflecth(x)[2:Ð1]

end

procedure scpal(x, i)
   local lseq

   /i := 1

   x := spromote(x)

   if i = 1 then return x ||| sreflecth(x)[2:0]
   else {
      lseq := srepeat(sopal(x), i)
      put(lseq, lseq[1])
      return lseq
      }

end

procedure sreflecth(x)
   local lseq

   lseq := []

   every push(lseq, !spromote(x))

   return lseq

end

procedure sreflectv(x)
   local lseq, m

   x := spromote(x)

   m := sbound ! x

   lseq := []

   every put(lseq, m Ð !x + 1)

   return lseq

end

procedure sbound(args[])

   return sort(args)[Ð1]		# last is largest

end

procedure slength(x)

   return *spromote(x)

end