even more refactoring

synced-pool.go

@@ -426,20 +426,13 @@ func (p *SyncedPool) getGrain(id CartId) (Grain, error) {
 	return grain, nil
 }
 
-// Process applies mutation(s) to a grain (local or remote).
-func (p *SyncedPool) Process(id CartId, mutations ...interface{}) (*CartGrain, error) {
+// Apply applies a single mutation to a grain (local or remote).
+func (p *SyncedPool) Apply(id CartId, mutation interface{}) (*CartGrain, error) {
 	grain, err := p.getGrain(id)
 	if err != nil {
 		return nil, err
 	}
-	var res *CartGrain
-	for _, m := range mutations {
-		res, err = grain.Apply(m, false)
-		if err != nil {
-			return nil, err
-		}
-	}
-	return res, nil
+	return grain.Apply(mutation, false)
 }
 
 // Get returns current state of a grain (local or remote).