During the lifecycle of a major release, new features are added and method

signatures and public API usages are changed. However,

:doc:`minor versions </cookbook/upgrade/minor_version` should not contain any

:doc:`minor versions</cookbook/upgrade/minor_version>` should not contain any

backwards compatibility changes. To accomplish this, the "old" (e.g. functions,

classes, etc) code still works, but is marked as *deprecated*, indicating that

it will be removed/changed in the future and that you should stop using it.