Decorum class runs wrapped function via a `call()` method

[benoitbryon]

At the moment, decorum.Decorum offers two entry points to customize decorators:

• init() setups the decorator instance;
• wraps() actually decorates the function.

What about adding a third one to run the wrapped function? It would be useful to customize things such as:

• alter input arguments
• post-process result

Overriding __call__() would be a bit tricky, because it does some magic, just like __init__(). That's why a new method would be appreciated.

[benoitbryon]

About the name: run() or call()? call() would mimic __init__() => init(). Whereas run() may avoid some confusions with __call__().

[zeekay]

Makes sense, I like call().