code: function _ensureExists(dir, callback) {
      dir = path.resolve(dir); // make full path
      
      path.exists(dir, function(exists) {
          if (!exists) {
              // ensure that the parent dir exists
              _ensureExists(path.dirname(dir), function(err) {
                  if (err) {
                      callback(err);
                      return;
                  }
                  
                  // make the dir
                  log.log('Creating ' + dir);
                  fs.mkdir(dir, function(err) {
                      if (err) {
                          callback(err);
                          return;
                      }
                      
                      callback(null);
                  });
              });
          }
          else {
              callback(null);
          }
      });
  }
docs: Ensures that a directory exists. If it doesn't, creates it and it's parents if needed.