OK, fair enough. What about "has whitespace (including Unicode beyond ASCII)"?
>>> import re
>>> r = re.compile(r'\s', re.U)
>>> r.search('ab\u2002cd')
<re.Match object; span=(2, 3), match='\u2002'>
❯ py -m timeit -s "import re; r = re.compile(r'\s', re.U)" "r.search('ab\u2002cd')"
1000000 loops, best of 5: 262 nsec per loop
Paul