diff --git a/src/Lexer2.cpp b/src/Lexer2.cpp
index d16eeff48..119a93d95 100644
--- a/src/Lexer2.cpp
+++ b/src/Lexer2.cpp
@@ -965,3 +965,9 @@ std::string Lexer2::typeToString (Lexer2::Type type)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+bool Lexer2::isAllDigits (const std::string& text)
+{
+  return text.find_first_not_of ("0123456789") == std::string::npos;
+}
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/src/Lexer2.h b/src/Lexer2.h
index 9cf3ea1e3..70cf99aa5 100644
--- a/src/Lexer2.h
+++ b/src/Lexer2.h
@@ -58,6 +58,7 @@ public:
   static std::vector <std::pair <std::string, Lexer2::Type>> tokens (const std::string&);
   static std::vector <std::string> split (const std::string&);
   static std::string typeToString (Lexer2::Type);
+  static bool isAllDigits (const std::string&);
 
   // Static helpers.
   static const std::string typeName (const Lexer2::Type&);