code: func (f *FileStore) Write(key string, data []byte) error {
  	if err := ValidateKey(key); err != nil {
  		return err
  	}
  	if err := ensureDirectory(f.filesystem, f.directoryPath); err != nil {
  		return err
  	}
  
  	return writeFile(f.filesystem, f.getPathByKey(key), data)
  }
docs: // Write writes the given data to a file named key.