sString$ = "[[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8 []]"

For siCount = 1 To Len(sString$)
	If Instr("[] ,", Mid$(sString$, siCount, 1)) = 0 Then
		sFlatter$ = sFlatter$ + sComma$ + Mid$(sString$, siCount, 1)
		sComma$ = ", "
	End If
Next siCount

Print "[", sFlatter$, "]"
End