code: func (c *Client) call(path string, in interface{}) (io.ReadCloser, error) {
  	url := "https://api.dropboxapi.com/2" + path
  
  	body, err := json.Marshal(in)
  	if err != nil {
  		return nil, err
  	}
  
  	req, err := http.NewRequest("POST", url, bytes.NewReader(body))
  	if err != nil {
  		return nil, err
  	}
  	req.Header.Set("Authorization", "Bearer "+c.AccessToken)
  	req.Header.Set("Content-Type", "application/json")
  
  	r, _, err := c.do(req)
  	return r, err
  }
docs: // call rpc style endpoint.