Possibly allow creating a custom parser with preset namespaces etc.

[facelessuser]

It might be nice to spawn a custom parser where you can just add your namespace mapping once, and all calls will pick it up. You could still do a one off call and manually feed them in, but you could also just create a custom parser and then just call as normal:

import soupsieve as sv

parser = sv.custom_parser()
parser.set_namespaces({"ns": "http:/ns.com"})
parser.select(':header.class', soup)