code: func (d *driver) PutContent(ctx context.Context, p string, contents []byte) error {
  	d.mutex.Lock()
  	defer d.mutex.Unlock()
  
  	normalized := normalize(p)
  
  	f, err := d.root.mkfile(normalized)
  	if err != nil {
  		// TODO(stevvooe): Again, we need to clarify when this is not a
  		// directory in StorageDriver API.
  		return fmt.Errorf("not a file")
  	}
  
  	f.truncate()
  	f.WriteAt(contents, 0)
  
  	return nil
  }
docs: // PutContent stores the []byte content at a location designated by "path".