Our understanding of typing.NamedTuple is lossy

It seems we can do a much better job over here:

- our current transform is losing the type of the arguments

- we should support typing.NamedTuple subclasses. I just added a basic support for it, but I don't feel it is enough, since we could store the types as well.

- it also seems that NamedTuple can have default values for its attributes

https://docs.python.org/3/library/typing.html#typing.NamedTuple

Start by locating the existing transform for typing.NamedTuple and read the linked Python documentation for subclass, field-type, and default-value behavior. Trace how the current transform represents arguments and attributes. Done means NamedTuple subclasses retain argument types and attribute defaults without losing information.

Written by the indexing model from the issue text.