diff --git a/a8/lisp.cc b/a8/lisp.cc
index a807dd7..e306d41 100644
--- a/a8/lisp.cc
+++ b/a8/lisp.cc
@@ -200,6 +200,11 @@ namespace a8
             return std::make_shared<Value>(stack[0]);
         }
 
+        bool Expr::MaybeExpr(const std::string& script)
+        {
+            return script.find('(') != std::string::npos;
+        }
+
         /*
           1: token
           -1: end
diff --git a/a8/lisp.h b/a8/lisp.h
index 82cc5f9..1c63858 100644
--- a/a8/lisp.h
+++ b/a8/lisp.h
@@ -77,6 +77,7 @@ namespace a8
 
             static std::shared_ptr<Value> Compile(const std::string& script, std::shared_ptr<Scope> env);
             static std::shared_ptr<Value> Eval(std::shared_ptr<Value> x, std::shared_ptr<Scope> env);
+            static bool MaybeExpr(const std::string& script);
 
         private:
             static int GetToken(const std::string& script, int& pos, std::string& token);