code: func (r Network_Storage_Backup_Evault) UpgradeVolumeCapacity(itemId *int) (resp bool, err error) {
  	params := []interface{}{
  		itemId,
  	}
  	err = r.Session.DoRequest("SoftLayer_Network_Storage_Backup_Evault", "upgradeVolumeCapacity", params, &r.Options, &resp)
  	return
  }
docs: // Upgrade the Storage volume to one of the upgradable packages (for example from 10 Gigs of EVault storage to 100 Gigs of EVault storage).