function nodeBeforeLocation(location) {
        var node;
        exports.root.each(function each(n) {
            if (!n.location || location < n.location) {
                return true;
            }
            if (!node || node.location < n.location) {
                node = n;
            }
        });
        return node;
    }
Get the last node before the given location
@param {integer} location