docs: function (binding, subpath, pred) {
      var args = Util.resolveArgs(
        arguments,
        'binding', function (x) { return Util.canRepresentSubpath(x) ? 'subpath' : null; }, '?pred'
      );
  
      return function (event) {
        var value = event.target.value;
        if (!args.pred || args.pred(value)) {
          binding.remove(args.subpath);
        }
      };
    }