#!/usr/local/bin/node
#!/usr/bin/js
var flipflop = function(p){
  return {
    p : 0,
    valueOf : function(){ return this.p = !this.p; },
    toString : valueOf
  };
};
var fl = flipflop();
console.log(+fl);
console.log(+fl);
console.log(+fl);
console.log(+fl);
console.log(fl);