lists = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

def format_list(items):
    list_contents = ' '.join(str(it) for it in items) # convert contents to string too
    return '[{}]'.format(list_contents) # wrap in brackets

formatted = format_list(format_list(l) for l in lists)

print formatted