human
I wrote the below code

    def f(msg):
        if ('successful_payment' in msg):
            return msg['successful_payment']['invoice_payload']
        else:
            return msg['invoice_payload']
    return _wrap_none(f)

What's a good function header?

=====
Here's a good function header?
assistant
#Here's a good function header.

def per_invoice_payload():