code: function() {
      this.expect('for');
      var key
        , val = this.id().name;
      if (this.accept(',')) key = this.id().name;
      this.expect('in');
      this.state.push('for');
      this.cond = true;
      var each = new nodes.Each(val, key, this.expression());
      this.cond = false;
      each.block = this.block(each, false);
      this.state.pop();
      return each;
    }
docs: for val (',' key) in expr