Add isDeleted (#2445)

docs/reference/game/is-deleted.md

@@ -0,0 +1,33 @@
+# Is Deleted
+
+Find out if the sprite is deleted from the game engine or not.
+
+```sig
+game.createSprite(0,0).isDeleted()
+```
+
+## Returns
+
+* a [boolean](/types/boolean) value that is `true` if the sprite is deleted from the game engine or `false` if not.
+
+## Example
+
+This game has 5 sprites initially. After 1 second, the third sprite is deleted and all remaining sprites are moved by 1.
+
+```blocks
+let sprites: game.LedSprite[] = []
+for (let i = 0; i <= 4; i++) {
+    sprites.push(game.createSprite(0, i))
+}
+basic.pause(1000)
+sprites[2].delete()
+for (let sprite of sprites) {
+    if (!(sprite.isDeleted())) {
+        sprite.move(1)
+    }
+}
+```
+
+## See also
+
+[delete sprite](/reference/game/delete)