Using Mapping type instead of Dict for TypedDict support

[Mazyod]

Thanks for this excellent project!

Would it make sense for arbitrary dictionaries, such as Document meta, to be type hinted as typing.Mapping? My reason is that I would like to utilize TypedDict for additional type hinting, but passing TypedDict instantiation to dict decorated functions upsets the type checker, and I have to do something like meta=dict(MyTypedDict(x=1)).

I wonder if it makes sense to "loosen" the type requirement by using Mapping instead?