Executes the specified function once for each item in the hash.
Returning false from the function will cease iteration.

@param {Function} fn The function to execute.
@param {String} fn.key The key of the item.
@param {Number} fn.value The value of the item.
@param {Number} fn.length The total number of items in the hash.
@param {Object} [scope] The scope to execute in. Defaults to <tt>this</tt>.
@return {Ext.util.HashMap} this
function(fn, scope) {
        // copy items so they may be removed during iteration.
        var items = Ext.apply({}, this.map),
            key,
            length = this.length;

        scope = scope || this;
        for (key in items) {
            if (items.hasOwnProperty(key)) {
                if (fn.call(scope, key, items[key], length) === false) {
                    break;
                }
            }
        }
        return this;
    }