import re
pattern = r"(?<!\S)(\w+)\([^()]*\)"
s = ("returnType ClassType functionName(int param1, double param2)\n"
"returnType ClassType functionName();\n"
"a(\n"
" a(")
print(re.findall(pattern, s))
aW1wb3J0IHJlCgpwYXR0ZXJuID0gciIoPzwhXFMpKFx3KylcKFteKCldKlwpIgoKcyA9ICgicmV0dXJuVHlwZSBDbGFzc1R5cGUgZnVuY3Rpb25OYW1lKGludCBwYXJhbTEsIGRvdWJsZSBwYXJhbTIpXG4iCiAgICAgICAgICAgICJyZXR1cm5UeXBlIENsYXNzVHlwZSBmdW5jdGlvbk5hbWUoKTtcbiIKICAgICAgICAgICAgImEoXG4iCiAgICAgICAgICAgICIgYSgiKQoKcHJpbnQocmUuZmluZGFsbChwYXR0ZXJuLCBzKSk=