Implement PEP 3131. Add isidentifier to str.
diff --git a/Include/errcode.h b/Include/errcode.h
index becec80..6bb3cc1 100644
--- a/Include/errcode.h
+++ b/Include/errcode.h
@@ -29,6 +29,7 @@
 #define E_EOFS		23	/* EOF in triple-quoted string */
 #define E_EOLS		24	/* EOL in single-quoted string */
 #define E_LINECONT	25	/* Unexpected characters after a line continuation */
+#define E_IDENTIFIER    26      /* Invalid characters in identifier */
 
 #ifdef __cplusplus
 }