and tag_cond_helper sexpr =
+    match sexpr with
+    | Pair(Pair(a, Pair(Symbol "=>", b)), Nil)  -> 
+      (Pair (Symbol "let", 
+        Pair(
+          Pair (Pair (Symbol "value", 
+              Pair (a, Nil)),
+                Pair
+          (Pair (Symbol "f",
+            Pair 
+            (Pair 
+            (Symbol "lambda", Pair (Nil, Pair (Pair(Symbol "begin", b), Nil))), Nil)),
+     Nil)),
+  Pair
+(Pair (Symbol "if",
+     Pair (Symbol "value",
+      Pair (Pair (Pair (Symbol "f", Nil), Pair (Symbol "value", Nil)), Nil))),
+   Nil))))