code: func ImportPrivateKey(ctx context.Context, c *cli.Context) error {
  	if err := initCrypto(); err != nil {
  		return action.ExitError(ctx, action.ExitUnknown, err, "failed to init XC")
  	}
  
  	file := c.String("file")
  
  	if file == "" {
  		return action.ExitError(ctx, action.ExitUsage, nil, "need file")
  	}
  
  	if !fsutil.IsFile(file) {
  		return action.ExitError(ctx, action.ExitNotFound, nil, "input file not found")
  	}
  
  	buf, err := ioutil.ReadFile(file)
  	if err != nil {
  		return action.ExitError(ctx, action.ExitIO, err, "failed to read file")
  	}
  	return crypto.ImportPrivateKey(ctx, buf)
  }
docs: // ImportPrivateKey imports an XC key