10 LET f$="["
20 LET n$="[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"
30 FOR i=2 TO (LEN n$)-1
40 IF n$(i)>"/" AND n$(i)<":" THEN LET f$=f$+n$(i): GO TO 60
50 IF n$(i)="," AND f$(LEN f$)<>"," THEN LET f$=f$+","
60 NEXT i
70 LET f$=f$+"]": PRINT f$