code: func (r Network_Backbone) GetGraphImage() (resp []byte, err error) {
  	err = r.Session.DoRequest("SoftLayer_Network_Backbone", "getGraphImage", nil, &r.Options, &resp)
  	return
  }
docs: // Retrieve a graph of a SoftLayer backbone's last 24 hours of activity. getGraphImage returns a PNG image measuring 827 pixels by 293 pixels.