stack, which calls the
resource's ``__exit__()`` method.

To register a cleanup function for something that isn't a
context manager, use :meth:`call_on_close`. Or use something
from :mod:`contextlib` to turn it into a context manager first.

.. code-block:: python

    @click.group()
    @click.option("--name")
    @click.pass_context
    def cli(ctx):
        ctx.obj = ctx.with_resource(connect_db(name))

:param context_manager: The context manager to enter.
:return: Whatever ``context_manager.__enter__()`` returns.

.. versionadded:: 8.0
)