+ * Note that if you define CCAN_STR_DEBUG, you will get extra compile
+ * checks on common misuses of the following functions (they will now
+ * be out-of-line, so there is a runtime penalty!).
+ *
+ * strstr, strchr, strrchr:
+ * Return const char * if first argument is const (gcc only).
+ *
+ * isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph,
+ * islower, isprint, ispunct, isspace, isupper, isxdigit:
+ * Static and runtime check that input is EOF or an *unsigned*
+ * char, as per C standard (really!).
+ *