Implement octal and hex escapes in strings.
diff --git a/py/misc.h b/py/misc.h
index 8756c25..52498c7 100644
--- a/py/misc.h
+++ b/py/misc.h
@@ -43,6 +43,7 @@
 bool unichar_isalpha(unichar c);
 bool unichar_isprint(unichar c);
 bool unichar_isdigit(unichar c);
+bool unichar_isxdigit(unichar c);
 
 /** string ******************************************************/