channel type - distinguishing between spot color vs alpha channels

[adamgreenhall]

Is your feature request related to a problem? Please describe.
I'm trying to read and write psd files that are CMYK+spot color. I'd like to be able to distinguish between channels which are spot colors and channels which are alpha channels (eg masks).

Describe the solution you'd like
The Photoshop API has something called ChannelType - is it possible to read/write ChannelType (or something similar) in psd-tools?

Describe alternatives you've considered
I've looked through the image_resources, but nothing there seems relevant

Here's an example file and a screenshot of that file in Photoshop, with what the different channels look - "light teal" is a spot color channel, while "Alpha 1" is an alpha channel