fix introduction example of aspectlib.Aspect

[german1608]

Today I was reading about this library and decided to take a look. I go ahead to the introduction to see how to use it. Then I saw the following example:

import aspectlib

@aspectlib.Aspect
def strip_return_value():
    result = yield aspectlib.Proceed
    yield aspectlib.Return(result.strip())

@strip_return_value
def read(name):
    return open(name).read()

When I call the read function, it throws the following exception:

Traceback (most recent call last):
  File "test.aspect.py", line 22, in <module>
    print(read('./test.aspect.py'))
  File "/home/german/env/local/lib/python2.7/site-packages/aspectlib/__init__.py", line 253, in advising_function_wrapper
    advisor = self.advising_function(*args, **kwargs)
TypeError: strip_return_value() takes no arguments (1 given)

The error is because a parameter is missing on the strip_return_value. I added *args, **kwargs just in case.
My runtime is the following:

• Python 2.7.12 (also happens on 3.5)
• aspectlib 1.4.2

[ionelmc]

Thanks!