Gets either the keys/values in an array from the hash.
@private
@param {Boolean} isKey True to extract the keys, otherwise, the value
@return {Array} An array of either keys/values from the hash.
function(isKey) {
        var arr = [],
            key,
            map = this.map;
        for (key in map) {
            if (map.hasOwnProperty(key)) {
                arr.push(isKey ? key: map[key]);
            }
        }
        return arr;
    }