The API for packages in core have no stability guarantee.
The packages within the core directory would normally be put into an
internal directory to prohibit their use outside the mongo directory.
However, some MongoDB tools require very low-level access to the building
blocks of a driver, so we have placed them into core to allow these
packages to be imported by projects that need them.
These package APIs may be modified in backwards-incompatible ways at any time.
You are strongly discouraged from directly using any packages in
core.