helper methods for new 3XX RDA fields?

[wearp]

RDA has brought with it three new fields which are mandatory according to the standard. They are

336 - Content Type
337 - Media Type
338 - Carrier Type

As they will (or should) appear in every RDA record, would helper methods for record.py for these be of interest to pymarc? Something along the lines of content_type(self), etc.

Let me know and I'd be happy to submit a pull.

[edsu]

I guess that would be fine. I've been kind of -0 on those helper methods being in there, but I guess they aren't hurting anyone.