function sillyfun (string foo, series x)
  series @foo_f1 = x+x(-1)+x(-2)+x(-3)
  series @foo_f2 = x+x(+1)
  list outlist = @foo_f1 @foo_f2
  return list outlist
end function

open data9-9
string sname="nocars"
list alist = sillyfun(sname, nocars)
print alist