code: func (r Hardware_SecurityModule) GetPublicBandwidthGraphImage(startTime *datatypes.Time, endTime *datatypes.Time) (resp []byte, err error) {
  	params := []interface{}{
  		startTime,
  		endTime,
  	}
  	err = r.Session.DoRequest("SoftLayer_Hardware_SecurityModule", "getPublicBandwidthGraphImage", params, &r.Options, &resp)
  	return
  }
docs: // Retrieve a graph of a server's public network bandwidth usage over the specified time frame. If no time frame is specified then getPublicBandwidthGraphImage retrieves the last 24 hours of public bandwidth usage. getPublicBandwidthGraphImage returns a PNG image measuring 827 pixels by 293 pixels.  THIS METHOD GENERATES GRAPHS BASED ON THE NEW DATA WAREHOUSE REPOSITORY.