code: function join() {
      var path = '';
      var args = slice.call(arguments, 0);
      if (arguments.length <= 1) args.unshift(cwd());
  
      for (var i = 0; i < args.length; i += 1) {
        var segment = args[i];
        if (!isString(segment)) {
          throw new TypeError ('Arguemnts to path.join must be strings');
        }
        if (segment) {
          if (!path) {
            path += segment;
          } else {
            path += '/' + segment;
          }
        }
      }
  
      return normalize(path);
    }
docs: join the pathes
  @param {String} [path1, path2, path3...]
  @return {String} joined path