Python Regex for a closing parenthesis without an opening parenthesis

I am looking to write a regex pattern than recognizes when my text has a single open parenthesis. I wrote this code below to search for a single left hand parenthesis with no right hand parenthesis. I tested the pattern on regex101.com, and it seems to recognize the pattern fine. But when I run this code below, it returns None.

str1='   8347(23402234'

test_this1=re.compile(r'''^\s*\([^\)]*$''',re.VERBOSE)
print(test_this1.match(str1))

I tested a similar code to identify if a string has only a closing parenthesis with no opening parenthesis.

str2='   834723402)234'

test_this2=re.compile(r'''^\s*[^\(]*\)$''',re.VERBOSE)
print(test_this2.match(str2))

Similarly this resulted in None even though regex101.com showed that it should recognize the string.

Is there a way to also combine the two and write a single regex pattern where it looks for any strings with an unpaired parenthesis?