var ops=D("^",True,  "*",'*,  "/",'/,  "+",'+,  "-",'-);

fcn parseRPN(e){
   println("\npostfix: ", e);
   stack:=L();
   foreach tok in (e.split()){
      op:=ops.find(tok);
      if(op){
	 y := stack.pop(); x := stack.pop();
	 if(True==op) x=x.pow(y);
	 else	      x=op(x,y);
	 stack.append(x);
      }
      else stack.append(tok.toFloat());
      println(tok," --> ",stack);
   }
   println("result: ", stack[0])
}