exception documentation

Subtype of RemovedIn20Warning to indicate an API that moved only.

Inherited from Base20DeprecationWarning:

Method __str__ Undocumented
Class Variable deprecated_since Indicates the version that started raising this deprecation warning

Inherited from HasDescriptionCode (via Base20DeprecationWarning, SADeprecationWarning):

Method __init__ Undocumented
Instance Variable code Undocumented
Method _code_str Undocumented