pack: Add format specifiers s#, + and +#

src/strbuffer.h

@@ -20,6 +20,8 @@ void strbuffer_close(strbuffer_t *strbuff);
 void strbuffer_clear(strbuffer_t *strbuff);
 
 const char *strbuffer_value(const strbuffer_t *strbuff);
+
+/* Steal the value and close the strbuffer */
 char *strbuffer_steal_value(strbuffer_t *strbuff);
 
 int strbuffer_append(strbuffer_t *strbuff, const char *string);