code: func (fs *Goofys) getInodeOrDie(id fuseops.InodeID) (inode *Inode) {
  	inode = fs.inodes[id]
  	if inode == nil {
  		panic(fmt.Sprintf("Unknown inode: %v", id))
  	}
  
  	return
  }
docs: // Find the given inode. Panic if it doesn't exist.
  //
  // LOCKS_REQUIRED(fs.mu)