[typecheck-users] How to accept NoneType

[shi d. <shi...@gm...>]

Hi,

I would like to define a class where an
attribute can be None.
For instance :
@accept(String, String)
class MyClass(a, b=None):
    if b:
        return b
    else:
        return a
I didn't find a way to use typecheck on this kind
of class. I tried to define String with
String = IsOneOf(str, unicode, NoneType) but it does
not work. It seems that 'None' can not
be checked. Have you any idea ?

Regards,
Marc.