Implement note spawner.

rhythm_game/note/visual/note_pool.gd

@@ -15,9 +15,21 @@ class_name NotePool extends Node
 @export var hold_skin: StringName = "default"
 
 func get_note(type: NoteVisual.TYPE) -> NoteVisual:
-	var note: NoteVisual
-	# TODO: Implement.
-	return note
+	match type:
+		NoteVisual.TYPE.TAP:
+			return get_tap()
+		NoteVisual.TYPE.HOLD:
+			return get_hold()
+		_:
+			return null
+
+func return_note(note: NoteVisual) -> void:
+	if note is TapNote:
+		note.reset()
+		return_tap(note as TapNote)
+	elif note is HoldNote:
+		note.reset()
+		return_hold(note as HoldNote)
 
 ## Get a tap note. Instantiates one if no free nodes are available.
 func get_tap() -> TapNote: