Add string methods

lib/application/app.go

@@ -45,7 +45,7 @@ func New(args ...string) (*App, error) {
 func (a *App) Run() error {
 	fmt.Printf("target: %d\n", a.Target)
 	for i, bucket := range a.Buckets {
-		fmt.Printf("bucket %d: %d\n", i+1, bucket.Capacity)
+		fmt.Printf("bucket %d: %s\n", i+1, bucket.String())
 	}
 	return nil
 }

lib/bucket/bucket.go

@@ -1,5 +1,7 @@
 package bucket
 
+import "fmt"
+
 // Bucket to store volume
 type Bucket struct {
 	// Capacity amount the bucket can store
@@ -29,3 +31,8 @@ func (b *Bucket) Pour(target *Bucket) {
 		target.Volume += availableVolume
 	}
 }
+
+// String gets string representation
+func (b *Bucket) String() string {
+	return fmt.Sprintf("%dvol/%dcap", b.Volume, b.Capacity)
+}