code: func (c *Files) Upload(in *UploadInput) (out *UploadOutput, err error) {
  	body, _, err := c.download("/files/upload", in, in.Reader)
  	if err != nil {
  		return
  	}
  	defer body.Close()
  
  	err = json.NewDecoder(body).Decode(&out)
  	return
  }
docs: // Upload a file smaller than 150MB.