Firewall on Demand

//     Underscore.js 1.1.6

//     (c) 2011 Jeremy Ashkenas, DocumentCloud Inc.

//     Underscore is freely distributable under the MIT license.

//     Portions of Underscore are inspired or borrowed from Prototype,

//     Oliver Steele's Functional, and John Resig's Micro-Templating.

//     For all details and documentation:

//     http://documentcloud.github.com/underscore

(function() {

  // Baseline setup

  // --------------

  // Establish the root object, `window` in the browser, or `global` on the server.

  var root = this;

  // Save the previous value of the `_` variable.

  var previousUnderscore = root._;

  // Establish the object that gets returned to break out of a loop iteration.

  var breaker = {};

  // Save bytes in the minified (but not gzipped) version:

  var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;

  // Create quick reference variables for speed access to core prototypes.

  var slice            = ArrayProto.slice,

      unshift          = ArrayProto.unshift,

      toString         = ObjProto.toString,

      hasOwnProperty   = ObjProto.hasOwnProperty;

  // All **ECMAScript 5** native function implementations that we hope to use

  // are declared here.

  var

    nativeForEach      = ArrayProto.forEach,

    nativeMap          = ArrayProto.map,

    nativeReduce       = ArrayProto.reduce,

    nativeReduceRight  = ArrayProto.reduceRight,

    nativeFilter       = ArrayProto.filter,

    nativeEvery        = ArrayProto.every,

    nativeSome         = ArrayProto.some,

    nativeIndexOf      = ArrayProto.indexOf,

    nativeLastIndexOf  = ArrayProto.lastIndexOf,

    nativeIsArray      = Array.isArray,

    nativeKeys         = Object.keys,

    nativeBind         = FuncProto.bind;

  // Create a safe reference to the Underscore object for use below.

  var _ = function(obj) { return new wrapper(obj); };

  // Export the Underscore object for **CommonJS**, with backwards-compatibility

  // for the old `require()` API. If we're not in CommonJS, add `_` to the

  // global object.

  if (typeof module !== 'undefined' && module.exports) {

    module.exports = _;

    _._ = _;

  } else {

    root._ = _;

  }

  // Current version.

  _.VERSION = '1.1.6';

  // Collection Functions

  // --------------------

  // The cornerstone, an `each` implementation, aka `forEach`.

  // Handles objects implementing `forEach`, arrays, and raw objects.

  // Delegates to **ECMAScript 5**'s native `forEach` if available.

  var each = _.each = _.forEach = function(obj, iterator, context) {

    if (obj == null) return;

    if (nativeForEach && obj.forEach === nativeForEach) {

      obj.forEach(iterator, context);

    } else if (_.isNumber(obj.length)) {

      for (var i = 0, l = obj.length; i < l; i++) {

        if (iterator.call(context, obj[i], i, obj) === breaker) return;

      }

    } else {

      for (var key in obj) {

        if (hasOwnProperty.call(obj, key)) {

          if (iterator.call(context, obj[key], key, obj) === breaker) return;

        }

      }

    }

  };

  // Return the results of applying the iterator to each element.

  // Delegates to **ECMAScript 5**'s native `map` if available.

  _.map = function(obj, iterator, context) {

    var results = [];

    if (obj == null) return results;

    if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);

    each(obj, function(value, index, list) {

      results[results.length] = iterator.call(context, value, index, list);

    });

    return results;

  };

  // **Reduce** builds up a single result from a list of values, aka `inject`,

  // or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.

  _.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {

    var initial = memo !== void 0;

    if (obj == null) obj = [];

    if (nativeReduce && obj.reduce === nativeReduce) {

      if (context) iterator = _.bind(iterator, context);

      return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);

    }

    each(obj, function(value, index, list) {

      if (!initial && index === 0) {

        memo = value;

        initial = true;

      } else {

        memo = iterator.call(context, memo, value, index, list);

      }

    });

    if (!initial) throw new TypeError("Reduce of empty array with no initial value");

    return memo;

  };

  // The right-associative version of reduce, also known as `foldr`.

  // Delegates to **ECMAScript 5**'s native `reduceRight` if available.

  _.reduceRight = _.foldr = function(obj, iterator, memo, context) {

    if (obj == null) obj = [];

    if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {

      if (context) iterator = _.bind(iterator, context);

      return memo !== void 0 ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);

    }

    var reversed = (_.isArray(obj) ? obj.slice() : _.toArray(obj)).reverse();

    return _.reduce(reversed, iterator, memo, context);

  };

  // Return the first value which passes a truth test. Aliased as `detect`.

  _.find = _.detect = function(obj, iterator, context) {

    var result;

    any(obj, function(value, index, list) {

      if (iterator.call(context, value, index, list)) {

        result = value;

        return true;

      }

    });

    return result;

  };

  // Return all the elements that pass a truth test.

  // Delegates to **ECMAScript 5**'s native `filter` if available.

  // Aliased as `select`.

  _.filter = _.select = function(obj, iterator, context) {

    var results = [];

    if (obj == null) return results;

    if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);

    each(obj, function(value, index, list) {

      if (iterator.call(context, value, index, list)) results[results.length] = value;

    });

    return results;

  };

  // Return all the elements for which a truth test fails.

  _.reject = function(obj, iterator, context) {

    var results = [];

    if (obj == null) return results;

    each(obj, function(value, index, list) {

      if (!iterator.call(context, value, index, list)) results[results.length] = value;

    });

    return results;

  };

  // Determine whether all of the elements match a truth test.

  // Delegates to **ECMAScript 5**'s native `every` if available.

  // Aliased as `all`.

  _.every = _.all = function(obj, iterator, context) {

    var result = true;

    if (obj == null) return result;

    if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);

    each(obj, function(value, index, list) {

      if (!(result = result && iterator.call(context, value, index, list))) return breaker;

    });

    return result;

  };

  // Determine if at least one element in the object matches a truth test.

  // Delegates to **ECMAScript 5**'s native `some` if available.

  // Aliased as `any`.

  var any = _.some = _.any = function(obj, iterator, context) {

    iterator || (iterator = _.identity);

    var result = false;

    if (obj == null) return result;

    if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);

    each(obj, function(value, index, list) {

      if (result = iterator.call(context, value, index, list)) return breaker;

    });

    return result;

  };

  // Determine if a given value is included in the array or object using `===`.

  // Aliased as `contains`.

  _.include = _.contains = function(obj, target) {

    var found = false;

    if (obj == null) return found;

    if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;

    any(obj, function(value) {

      if (found = value === target) return true;

    });

    return found;

  };

  // Invoke a method (with arguments) on every item in a collection.

  _.invoke = function(obj, method) {

    var args = slice.call(arguments, 2);

    return _.map(obj, function(value) {

      return (method.call ? method || value : value[method]).apply(value, args);

    });

  };

  // Convenience version of a common use case of `map`: fetching a property.

  _.pluck = function(obj, key) {

    return _.map(obj, function(value){ return value[key]; });

  };

  // Return the maximum element or (element-based computation).

  _.max = function(obj, iterator, context) {

    if (!iterator && _.isArray(obj)) return Math.max.apply(Math, obj);

    var result = {computed : -Infinity};

    each(obj, function(value, index, list) {

      var computed = iterator ? iterator.call(context, value, index, list) : value;

      computed >= result.computed && (result = {value : value, computed : computed});

    });

    return result.value;

  };

  // Return the minimum element (or element-based computation).

  _.min = function(obj, iterator, context) {

    if (!iterator && _.isArray(obj)) return Math.min.apply(Math, obj);

    var result = {computed : Infinity};

    each(obj, function(value, index, list) {

      var computed = iterator ? iterator.call(context, value, index, list) : value;

      computed < result.computed && (result = {value : value, computed : computed});

    });

    return result.value;

  };

  // Sort the object's values by a criterion produced by an iterator.

  _.sortBy = function(obj, iterator, context) {

    return _.pluck(_.map(obj, function(value, index, list) {

      return {

        value : value,

        criteria : iterator.call(context, value, index, list)

      };

    }).sort(function(left, right) {

      var a = left.criteria, b = right.criteria;

      return a < b ? -1 : a > b ? 1 : 0;

    }), 'value');

  };

  // Use a comparator function to figure out at what index an object should

  // be inserted so as to maintain order. Uses binary search.

  _.sortedIndex = function(array, obj, iterator) {

    iterator || (iterator = _.identity);

    var low = 0, high = array.length;

    while (low < high) {

      var mid = (low + high) >> 1;

      iterator(array[mid]) < iterator(obj) ? low = mid + 1 : high = mid;

    }

    return low;

  };

  // Safely convert anything iterable into a real, live array.

  _.toArray = function(iterable) {

    if (!iterable)                return [];

    if (iterable.toArray)         return iterable.toArray();

    if (_.isArray(iterable))      return iterable;

    if (_.isArguments(iterable))  return slice.call(iterable);

    return _.values(iterable);

  };

  // Return the number of elements in an object.

  _.size = function(obj) {

    return _.toArray(obj).length;

  };

  // Array Functions

  // ---------------

  // Get the first element of an array. Passing **n** will return the first N

  // values in the array. Aliased as `head`. The **guard** check allows it to work

  // with `_.map`.

  _.first = _.head = function(array, n, guard) {

    return (n != null) && !guard ? slice.call(array, 0, n) : array[0];

  };

  // Returns everything but the first entry of the array. Aliased as `tail`.

  // Especially useful on the arguments object. Passing an **index** will return

  // the rest of the values in the array from that index onward. The **guard**

  // check allows it to work with `_.map`.

  _.rest = _.tail = function(array, index, guard) {

    return slice.call(array, (index == null) || guard ? 1 : index);

  };

  // Get the last element of an array.

  _.last = function(array) {

    return array[array.length - 1];

  };

  // Trim out all falsy values from an array.

  _.compact = function(array) {

    return _.filter(array, function(value){ return !!value; });

  };

  // Return a completely flattened version of an array.

  _.flatten = function(array) {

    return _.reduce(array, function(memo, value) {

      if (_.isArray(value)) return memo.concat(_.flatten(value));

      memo[memo.length] = value;

      return memo;

    }, []);

  };

  // Return a version of the array that does not contain the specified value(s).

  _.without = function(array) {

    var values = slice.call(arguments, 1);

    return _.filter(array, function(value){ return !_.include(values, value); });

  };

  // Produce a duplicate-free version of the array. If the array has already

  // been sorted, you have the option of using a faster algorithm.

  // Aliased as `unique`.

  _.uniq = _.unique = function(array, isSorted) {

    return _.reduce(array, function(memo, el, i) {

      if (0 == i || (isSorted === true ? _.last(memo) != el : !_.include(memo, el))) memo[memo.length] = el;

      return memo;

    }, []);

  };

  // Produce an array that contains every item shared between all the

  // passed-in arrays.

  _.intersect = function(array) {

    var rest = slice.call(arguments, 1);

    return _.filter(_.uniq(array), function(item) {

      return _.every(rest, function(other) {

        return _.indexOf(other, item) >= 0;

      });

    });

  };

  // Zip together multiple lists into a single array -- elements that share

  // an index go together.

  _.zip = function() {

    var args = slice.call(arguments);

    var length = _.max(_.pluck(args, 'length'));

    var results = new Array(length);

    for (var i = 0; i < length; i++) results[i] = _.pluck(args, "" + i);

    return results;

  };

  // If the browser doesn't supply us with indexOf (I'm looking at you, **MSIE**),

  // we need this function. Return the position of the first occurrence of an

  // item in an array, or -1 if the item is not included in the array.

  // Delegates to **ECMAScript 5**'s native `indexOf` if available.

  // If the array is large and already in sort order, pass `true`

  // for **isSorted** to use binary search.

  _.indexOf = function(array, item, isSorted) {

    if (array == null) return -1;

    var i, l;

    if (isSorted) {

      i = _.sortedIndex(array, item);

      return array[i] === item ? i : -1;

    }

    if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item);

    for (i = 0, l = array.length; i < l; i++) if (array[i] === item) return i;

    return -1;

  };

  // Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.

  _.lastIndexOf = function(array, item) {

    if (array == null) return -1;

    if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) return array.lastIndexOf(item);

    var i = array.length;

    while (i--) if (array[i] === item) return i;

    return -1;

  };

  // Generate an integer Array containing an arithmetic progression. A port of

  // the native Python `range()` function. See

  // [the Python documentation](http://docs.python.org/library/functions.html#range).

  _.range = function(start, stop, step) {

    if (arguments.length <= 1) {

      stop = start || 0;

      start = 0;

    }

    step = arguments[2] || 1;

    var len = Math.max(Math.ceil((stop - start) / step), 0);

    var idx = 0;

    var range = new Array(len);

    while(idx < len) {

      range[idx++] = start;

      start += step;

    }

    return range;

  };

  // Function (ahem) Functions

  // ------------------

  // Create a function bound to a given object (assigning `this`, and arguments,

  // optionally). Binding with arguments is also known as `curry`.

  // Delegates to **ECMAScript 5**'s native `Function.bind` if available.

  // We check for `func.bind` first, to fail fast when `func` is undefined.

  _.bind = function(func, obj) {

    if (func.bind === nativeBind && nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));

    var args = slice.call(arguments, 2);

    return function() {

      return func.apply(obj, args.concat(slice.call(arguments)));

    };

  };

  // Bind all of an object's methods to that object. Useful for ensuring that

  // all callbacks defined on an object belong to it.

  _.bindAll = function(obj) {

    var funcs = slice.call(arguments, 1);

    if (funcs.length == 0) funcs = _.functions(obj);

    each(funcs, function(f) { obj[f] = _.bind(obj[f], obj); });

    return obj;

  };

  // Memoize an expensive function by storing its results.

  _.memoize = function(func, hasher) {

    var memo = {};

    hasher || (hasher = _.identity);

    return function() {

      var key = hasher.apply(this, arguments);

      return hasOwnProperty.call(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));

    };

  };

  // Delays a function for the given number of milliseconds, and then calls

  // it with the arguments supplied.

  _.delay = function(func, wait) {

    var args = slice.call(arguments, 2);

    return setTimeout(function(){ return func.apply(func, args); }, wait);

  };

  // Defers a function, scheduling it to run after the current call stack has

  // cleared.

  _.defer = function(func) {

    return _.delay.apply(_, [func, 1].concat(slice.call(arguments, 1)));

  };

  // Internal function used to implement `_.throttle` and `_.debounce`.

  var limit = function(func, wait, debounce) {

    var timeout;

    return function() {

      var context = this, args = arguments;

      var throttler = function() {

        timeout = null;

        func.apply(context, args);

      };

      if (debounce) clearTimeout(timeout);

      if (debounce || !timeout) timeout = setTimeout(throttler, wait);

    };

  };

  // Returns a function, that, when invoked, will only be triggered at most once

  // during a given window of time.

  _.throttle = function(func, wait) {

    return limit(func, wait, false);

  };

  // Returns a function, that, as long as it continues to be invoked, will not

  // be triggered. The function will be called after it stops being called for

  // N milliseconds.

  _.debounce = function(func, wait) {

    return limit(func, wait, true);

  };

  // Returns a function that will be executed at most one time, no matter how

  // often you call it. Useful for lazy initialization.

  _.once = function(func) {

    var ran = false, memo;

    return function() {

      if (ran) return memo;

      ran = true;

      return memo = func.apply(this, arguments);

    };

  };

  // Returns the first function passed as an argument to the second,

  // allowing you to adjust arguments, run code before and after, and

  // conditionally execute the original function.

  _.wrap = function(func, wrapper) {

    return function() {

      var args = [func].concat(slice.call(arguments));

      return wrapper.apply(this, args);

    };

  };

  // Returns a function that is the composition of a list of functions, each

  // consuming the return value of the function that follows.

  _.compose = function() {

    var funcs = slice.call(arguments);

    return function() {

      var args = slice.call(arguments);

      for (var i=funcs.length-1; i >= 0; i--) {

        args = [funcs[i].apply(this, args)];

      }

      return args[0];

    };

  };

  // Returns a function that will only be executed after being called N times.

  _.after = function(times, func) {

    return function() {

      if (--times < 1) { return func.apply(this, arguments); }

    };

  };

  // Object Functions

  // ----------------

  // Retrieve the names of an object's properties.

  // Delegates to **ECMAScript 5**'s native `Object.keys`

  _.keys = nativeKeys || function(obj) {

    if (obj !== Object(obj)) throw new TypeError('Invalid object');

    var keys = [];

    for (var key in obj) if (hasOwnProperty.call(obj, key)) keys[keys.length] = key;

    return keys;

  };

  // Retrieve the values of an object's properties.

  _.values = function(obj) {

    return _.map(obj, _.identity);

  };

  // Return a sorted list of the function names available on the object.

  // Aliased as `methods`

  _.functions = _.methods = function(obj) {

    return _.filter(_.keys(obj), function(key){ return _.isFunction(obj[key]); }).sort();

  };

  // Extend a given object with all the properties in passed-in object(s).

  _.extend = function(obj) {

    each(slice.call(arguments, 1), function(source) {

      for (var prop in source) {

        if (source[prop] !== void 0) obj[prop] = source[prop];

      }

    });

    return obj;

  };

  // Fill in a given object with default properties.

  _.defaults = function(obj) {

    each(slice.call(arguments, 1), function(source) {

      for (var prop in source) {

        if (obj[prop] == null) obj[prop] = source[prop];

      }

    });

    return obj;

  };

  // Create a (shallow-cloned) duplicate of an object.

  _.clone = function(obj) {

    return _.isArray(obj) ? obj.slice() : _.extend({}, obj);

  };

  // Invokes interceptor with the obj, and then returns obj.

  // The primary purpose of this method is to "tap into" a method chain, in

  // order to perform operations on intermediate results within the chain.

  _.tap = function(obj, interceptor) {

    interceptor(obj);

    return obj;

  };

  // Perform a deep comparison to check if two objects are equal.

  _.isEqual = function(a, b) {

    // Check object identity.

    if (a === b) return true;

    // Different types?

    var atype = typeof(a), btype = typeof(b);

    if (atype != btype) return false;

    // Basic equality test (watch out for coercions).

    if (a == b) return true;

    // One is falsy and the other truthy.

    if ((!a && b) || (a && !b)) return false;

    // Unwrap any wrapped objects.

    if (a._chain) a = a._wrapped;

    if (b._chain) b = b._wrapped;

    // One of them implements an isEqual()?

    if (a.isEqual) return a.isEqual(b);

    // Check dates' integer values.

    if (_.isDate(a) && _.isDate(b)) return a.getTime() === b.getTime();

    // Both are NaN?

    if (_.isNaN(a) && _.isNaN(b)) return false;

    // Compare regular expressions.

    if (_.isRegExp(a) && _.isRegExp(b))

      return a.source     === b.source &&

             a.global     === b.global &&

             a.ignoreCase === b.ignoreCase &&

             a.multiline  === b.multiline;

    // If a is not an object by this point, we can't handle it.

    if (atype !== 'object') return false;

    // Check for different array lengths before comparing contents.

    if (a.length && (a.length !== b.length)) return false;

    // Nothing else worked, deep compare the contents.

    var aKeys = _.keys(a), bKeys = _.keys(b);

    // Different object sizes?

    if (aKeys.length != bKeys.length) return false;

    // Recursive comparison of contents.

    for (var key in a) if (!(key in b) || !_.isEqual(a[key], b[key])) return false;

    return true;

  };

  // Is a given array or object empty?

  _.isEmpty = function(obj) {

    if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;

    for (var key in obj) if (hasOwnProperty.call(obj, key)) return false;

    return true;

  };

  // Is a given value a DOM element?

  _.isElement = function(obj) {

    return !!(obj && obj.nodeType == 1);

  };

  // Is a given value an array?

  // Delegates to ECMA5's native Array.isArray

  _.isArray = nativeIsArray || function(obj) {

    return toString.call(obj) === '[object Array]';

  };

  // Is a given variable an arguments object?

  _.isArguments = function(obj) {

    return !!(obj && hasOwnProperty.call(obj, 'callee'));

  };

  // Is a given value a function?

  _.isFunction = function(obj) {

    return !!(obj && obj.constructor && obj.call && obj.apply);

  };

  // Is a given value a string?

  _.isString = function(obj) {

    return !!(obj === '' || (obj && obj.charCodeAt && obj.substr));

  };

  // Is a given value a number?

  _.isNumber = function(obj) {

    return !!(obj === 0 || (obj && obj.toExponential && obj.toFixed));

  };

  // Is the given value `NaN`? `NaN` happens to be the only value in JavaScript

  // that does not equal itself.

  _.isNaN = function(obj) {

    return obj !== obj;

  };

  // Is a given value a boolean?

  _.isBoolean = function(obj) {

    return obj === true || obj === false;

  };

  // Is a given value a date?

  _.isDate = function(obj) {

    return !!(obj && obj.getTimezoneOffset && obj.setUTCFullYear);

  };

  // Is the given value a regular expression?

  _.isRegExp = function(obj) {

    return !!(obj && obj.test && obj.exec && (obj.ignoreCase || obj.ignoreCase === false));

  };

  // Is a given value equal to null?

  _.isNull = function(obj) {

    return obj === null;

  };

  // Is a given variable undefined?

  _.isUndefined = function(obj) {

    return obj === void 0;

  };

  // Utility Functions

  // -----------------

  // Run Underscore.js in *noConflict* mode, returning the `_` variable to its

  // previous owner. Returns a reference to the Underscore object.

  _.noConflict = function() {

    root._ = previousUnderscore;

    return this;

  };

  // Keep the identity function around for default iterators.

  _.identity = function(value) {

    return value;

  };

  // Run a function **n** times.

  _.times = function (n, iterator, context) {

    for (var i = 0; i < n; i++) iterator.call(context, i);

  };

  // Add your own custom functions to the Underscore object, ensuring that

  // they're correctly added to the OOP wrapper as well.

  _.mixin = function(obj) {

    each(_.functions(obj), function(name){

      addToWrapper(name, _[name] = obj[name]);

    });

  };

  // Generate a unique integer id (unique within the entire client session).

  // Useful for temporary DOM ids.

  var idCounter = 0;

  _.uniqueId = function(prefix) {

    var id = idCounter++;

    return prefix ? prefix + id : id;

  };

  // By default, Underscore uses ERB-style template delimiters, change the

  // following template settings to use alternative delimiters.

  _.templateSettings = {

    evaluate    : /<%([\s\S]+?)%>/g,

    interpolate : /<%=([\s\S]+?)%>/g

  };

  // JavaScript micro-templating, similar to John Resig's implementation.

  // Underscore templating handles arbitrary delimiters, preserves whitespace,

  // and correctly escapes quotes within interpolated code.

  _.template = function(str, data) {

    var c  = _.templateSettings;

    var tmpl = 'var __p=[],print=function(){__p.push.apply(__p,arguments);};' +

      'with(obj||{}){__p.push(\'' +

      str.replace(/\\/g, '\\\\')

         .replace(/'/g, "\\'")

         .replace(c.interpolate, function(match, code) {

           return "'," + code.replace(/\\'/g, "'") + ",'";

         })

         .replace(c.evaluate || null, function(match, code) {

           return "');" + code.replace(/\\'/g, "'")

                              .replace(/[\r\n\t]/g, ' ') + "__p.push('";

         })

         .replace(/\r/g, '\\r')

         .replace(/\n/g, '\\n')

         .replace(/\t/g, '\\t')

         + "');}return __p.join('');";

    var func = new Function('obj', tmpl);

    return data ? func(data) : func;

  };

  // The OOP Wrapper

  // ---------------

  // If Underscore is called as a function, it returns a wrapped object that

  // can be used OO-style. This wrapper holds altered versions of all the

  // underscore functions. Wrapped objects may be chained.

  var wrapper = function(obj) { this._wrapped = obj; };

  // Expose `wrapper.prototype` as `_.prototype`

  _.prototype = wrapper.prototype;

  // Helper function to continue chaining intermediate results.

  var result = function(obj, chain) {

    return chain ? _(obj).chain() : obj;

  };

  // A method to easily add functions to the OOP wrapper.

  var addToWrapper = function(name, func) {

    wrapper.prototype[name] = function() {

      var args = slice.call(arguments);

      unshift.call(args, this._wrapped);

      return result(func.apply(_, args), this._chain);

    };

  };

  // Add all of the Underscore functions to the wrapper object.

  _.mixin(_);

  // Add all mutator Array functions to the wrapper.

  each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {

    var method = ArrayProto[name];

    wrapper.prototype[name] = function() {

      method.apply(this._wrapped, arguments);

      return result(this._wrapped, this._chain);

    };

  });

  // Add all accessor Array functions to the wrapper.

  each(['concat', 'join', 'slice'], function(name) {

    var method = ArrayProto[name];

    wrapper.prototype[name] = function() {

      return result(method.apply(this._wrapped, arguments), this._chain);

    };

  });

  // Start chaining a wrapped Underscore object.

  wrapper.prototype.chain = function() {

    this._chain = true;

    return this;

  };

  // Extracts the result from a wrapped and chained object.

  wrapper.prototype.value = function() {

    return this._wrapped;

  };

})();