# -*- coding: UTF-8 -*
def log(func):
    def decorator(func1):
        def wrapper(*args, **kw):
            print('begin call')
            result = func1(*args, **kw)
            print('end call')
            return result
        return wrapper

    if isinstance(func, str):
        return decorator
    else:
        return decorator(func)

@log
def f():
    print('f is invoked')

print(f.__name__)
f()