1 files changed, 9 insertions, 0 deletions
diff --git a/Include/stringobject.h b/Include/stringobject.h
index 3deea8f..0c7e5b6 100644
--- a/Include/stringobject.h
+++ b/Include/stringobject.h
@@ -37,6 +37,15 @@ typedef struct {
     long ob_shash;
     int ob_sstate;
     char ob_sval[1];
+
+    /* Invariants:
+     *     ob_sval contains space for 'ob_size+1' elements.
+     *     ob_sval[ob_size] == 0.
+     *     ob_shash is the hash of the string or -1 if not computed yet.
+     *     ob_sstate != 0 iff the string object is in stringobject.c's
+     *       'interned' dictionary; in this case the two references
+     *       from 'interned' to this object are *not counted* in ob_refcnt.
+     */
 } PyStringObject;
 
 #define SSTATE_NOT_INTERNED 0