code: func (ss *scaleSet) getVmssVMByInstanceID(resourceGroup, scaleSetName, instanceID string) (vm compute.VirtualMachineScaleSetVM, err error) {
  	vmName := ss.makeVmssVMName(scaleSetName, instanceID)
  	key := buildVmssCacheKey(resourceGroup, vmName)
  	cachedVM, err := ss.vmssVMCache.Get(key)
  	if err != nil {
  		return vm, err
  	}
  
  	if cachedVM == nil {
  		klog.Errorf("couldn't find vmss virtual machine by scaleSetName (%s) and instanceID (%s)", scaleSetName, instanceID)
  		return vm, cloudprovider.InstanceNotFound
  	}
  
  	return *(cachedVM.(*compute.VirtualMachineScaleSetVM)), nil
  }
docs: // getCachedVirtualMachineByInstanceID gets scaleSetVMInfo from cache.
  // The node must belong to one of scale sets.