Thanks for this awesome library!
I found make_key_iterator which would be nice for exposing map-like classes, but I didn't see it in the API reference document. Is it public? Also, I only find make_iterator in an example snippet https://pybind11.readthedocs.io/en/stable/advanced/cast/stl.html?highlight=make_iterator#making-opaque-types but not in the reference. Is that expected? Would be nice to have a bit more detail in the API reference.