code: func (c *Client) responseJSONMap(requestName string, resp *http.Response) (map[string]interface{}, error) {
  	if resp.StatusCode != 200 {
  		c.printf("After %s request, failed to JSON from response; status code is %d", requestName, resp.StatusCode)
  		io.Copy(os.Stderr, resp.Body)
  		return nil, fmt.Errorf("after %s request, HTTP response code is %d; no JSON to parse", requestName, resp.StatusCode)
  	}
  	jmap := make(map[string]interface{})
  	if err := httputil.DecodeJSON(resp, &jmap); err != nil {
  		return nil, err
  	}
  	return jmap, nil
  }
docs: // TODO(bradfitz): delete most of this. use new camlistore.org/pkg/blobserver/protocol types instead
  // of a map[string]interface{}.