10 CLS
20 S$ = "[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"
30 FOR SICOUNT = 1 TO LEN(S$)
40   IF INSTR("[] ,",MID$(S$,SICOUNT,1)) = 0 THEN SFLATTER$ = SFLATTER$+SCOMMA$+MID$(S$,SICOUNT,1): SCOMMA$ = ", "
50 NEXT SICOUNT
60 PRINT "[";SFLATTER$;"]"
70 END