code: func (r Account) GetHistoricalBandwidthGraph(startDate *datatypes.Time, endDate *datatypes.Time) (resp datatypes.Container_Account_Graph_Outputs, err error) {
  	params := []interface{}{
  		startDate,
  		endDate,
  	}
  	err = r.Session.DoRequest("SoftLayer_Account", "getHistoricalBandwidthGraph", params, &r.Options, &resp)
  	return
  }
docs: // This method will return a SoftLayer_Container_Account_Graph_Outputs object containing a base64 string PNG image of a line graph of bandwidth statistics given the start and end dates. The start and end dates should be valid ISO 8601 date formatted strings.