update: slice exercises 21, 23, 24, 25, 26

16-slices/exercises/21-correct-the-lyric/hints.md

@@ -0,0 +1,17 @@
+# Hints
+
+You can use the following slice operations to solve the exercise:
+
++ Prepends "value" to the slice:
+  ```go
+  slice = append([]string{"value"}, slice...)
+  ```
+
++ Appends some part (N to M) of the same slice to itself:
+  ```go
+  slice = append(slice, slice[N:M]...)
+  ```
++ Copies the last part of the slice starting from M to the first part of the slice until N:
+  ```go
+  slice = append(slice[:N], slice[M:]...)
+  ```