code: func TrySharedKeyLock(lockDir string, key string) (*KeyLock, error) {
  	return createAndLock(lockDir, key, keyLockShared|keyLockNonBlocking)
  }
docs: // TrySharedLock takes a co-operative (shared) lock on a key without blocking.
  // lockDir is the directory where the lock file will be created.
  // It will return ErrLocked if an exclusive lock already exists on the key.