This is important if external packages want to refer to the type.

This conforms to the docstring of the defgeneric.

Make it so ASDF 3.3 and LIFT won't complain.

Fix concurrency issue in red-black-tree

The old implementation used a global *RBT-EMPTY-NODE* for all instanced
of red-black-tree. This caused an error when multiple threads were
updating different trees at the same time.

Further discussion here: https://github.com/gwkkwg/cl-containers/issues/6

Fix the cl-containers-test.asd file to remove a non-existent static file.

darcs-hash:20091025182950-3cc5d-531a8fdaa01b7c13c0682f15e7107b6bc2c4f7ab.gz

darcs-hash:20090427022527-3cc5d-99a714683256749056c41908a14a367ae400dca3.gz

darcs-hash:20090427022521-3cc5d-cf71cb4a9e57f6983ffb5f026811c167ac0dd0a6.gz

darcs-hash:20090308154810-3cc5d-5b00e88023a83e321781f6bd060524fba62a084c.gz

darcs-hash:20090308154728-3cc5d-9c981088b219b84411165761d630d05b29bbc47a.gz

darcs-hash:20090308154706-3cc5d-d440e215149ba4daa477d792b03773dc9cb737f2.gz

darcs-hash:20090307191211-783f4-e7c7aa3dc635c897b35ab6a6d8f2e335cb62840b.gz

The one chunk of code in here (not active) got fixed up and moved to the other trees test file.

darcs-hash:20090307191034-783f4-a10e099f0f75661c4c9877c0091b65f574ccfb6a.gz

darcs-hash:20090307191014-783f4-ae6261053abc2d81be23d6bcf35ab7f76813daf8.gz

When searching for an item in a bst, make sure that the node isn't a placeholder and actually has an element

darcs-hash:20090306165250-783f4-efc295b7febc5c1caeaa2561184af6169e16a924.gz

darcs-hash:20090206172340-3cc5d-8faeaa9b7c51f1f7467bf4c2bbb560b08bf06a76.gz

darcs-hash:20090206164543-3cc5d-fc804c006137b20db417faa976e3c961407aeb00.gz