code: func (ctx *workflowContext) registerFinalizer(userFunction finalizerFunction) {
  	if nil == ctx.transaction.finalizerFunctions || len(ctx.transaction.finalizerFunctions) <= 0 {
  		ctx.transaction.finalizerFunctions = make([]finalizerFunction, 0)
  	}
  	ctx.transaction.finalizerFunctions = append(ctx.transaction.finalizerFunctions, userFunction)
  }
docs: // Register a rollback function in the event that the provisioning
  // function failed.