+/* Try to colorize some source code. FILENAME is the name of the file
+ holding the code. CONTENTS is the source code itself. This will
+ either a colorized (using ANSI terminal escapes) version of the
+ source code, or an empty value if colorizing could not be done. */
+
+extern gdb::optional<std::string> ext_lang_colorize
+ (const std::string &filename, const std::string &contents);
+