code: func (r Network_ContentDelivery_Account) GetDiskSpaceUsageImageByDate(beginDateTime *datatypes.Time, endDateTime *datatypes.Time) (resp datatypes.Container_Bandwidth_GraphOutputs, err error) {
  	params := []interface{}{
  		beginDateTime,
  		endDateTime,
  	}
  	err = r.Session.DoRequest("SoftLayer_Network_ContentDelivery_Account", "getDiskSpaceUsageImageByDate", params, &r.Options, &resp)
  	return
  }
docs: // This method returns a disk usage graph wrapped in [[SoftLayer_Container_Bandwidth_GraphOutputsExtended|Bandwidth Graph]] object. [[SoftLayer_Container_Bandwidth_GraphOutputsExtended|Bandwidth Graph]] object contains a starting time, ending time, graph title, graph binary data, and in and outbound total bytes.