diff --git a/std/string/array/dup.lb b/std/string/array/dup.lb
new file mode 100644
index 0000000..92df444
--- /dev/null
+++ b/std/string/array/dup.lb
@@ -0,0 +1,2 @@
+@ 0
+ args 0
diff --git a/std/string/array/rev.lb b/std/string/array/rev.lb
new file mode 100644
index 0000000..b58286b
--- /dev/null
+++ b/std/string/array/rev.lb
@@ -0,0 +1,2 @@
+args 0
+size
diff --git a/std/string/null/rev.lb b/std/string/null/rev.lb
new file mode 100644
index 0000000..e671aaf
--- /dev/null
+++ b/std/string/null/rev.lb
@@ -0,0 +1,12 @@
+@ 0
+ args 1
+ kjz 1
+ jmp 0
+
+@ 1
+ pop
+ size
+ #exec std/rev.lb
+ push 0
+ size
+ #exec std/rev.lb