code: function mkdirsInner(dirnames, currentPath, callback) {
      // Check for completion and call callback
      if (dirnames.length === 0) {
        return _callback(callback);
      }
  
      // Make next directory
      var dirname = dirnames.shift();
      currentPath = path.join(currentPath, dirname);
      fs.mkdir(currentPath, function(err) {
        return mkdirsInner(dirnames, currentPath, callback);
      });
    }
docs: Run async mkdir recursively