Exception vs instance checking

bench.py

class TestClass:
    def testmethod(self):
        return 5, 3

def test(a):
    try:
        meth = a.testmethod
    except AttributeError:
        return a, 3
    else:
        return meth()

def test2(a):
    if not isinstance(a, TestClass):
        return a, 3
    return a.testmethod()

if __name__ == '__main__':
    import timeit
    print("Try/Except - Except: %.03f" % timeit.timeit("test(5)", setup="from __main__ import test, TestClass"))
    print("Try/Except - Else:   %.03f" % timeit.timeit("test(TestClass())", setup="from __main__ import test, TestClass"))
    print("isinstance - No:     %.03f" %  timeit.timeit("test2(5)", setup="from __main__ import test2, TestClass"))
    print("isinstance - Yes:    %.03f" % timeit.timeit("test2(TestClass())", setup="from __main__ import test2, TestClass"))
~                                                                                                                            

Can you also try:

def test3(a):
    meth = getattr(a, "testmethod", None)
    if meth is None:
        return a, 3
    return meth()