+ (let* ((*bq-error*
+ (if (zerop *backquote-count*)
+ *bq-error*
+ "Comma inside backquoted structure (not a list or general vector.)"))
+ (*backquote-count* 0)
+ (body (if (char= (read-char stream t) #\( )
+ (let ((*backquote-count* 0))
+ (read-list stream nil))