code: func (c *Client) Get(ctx context.Context, container, key string) (body io.ReadCloser, size int64, err error) {
  	req := newReq(ctx, c.keyURL(container, key))
  	c.Auth.SignRequest(req)
  	res, err := c.transport().RoundTrip(req)
  	if err != nil {
  		return
  	}
  	switch res.StatusCode {
  	case http.StatusOK:
  		return res.Body, res.ContentLength, nil
  	case http.StatusNotFound:
  		res.Body.Close()
  		return nil, 0, os.ErrNotExist
  	default:
  		res.Body.Close()
  		return nil, 0, fmt.Errorf("azure HTTP error on GET: %d", res.StatusCode)
  	}
  }
docs: // Get retrieves a blob from Azure or returns os.ErrNotExist if not found