5.3.13
(fix): Fix NameError when a type uses extends to inherit from a base type in a different
file and that base type is part of a circular reference cycle. The generator was
incorrectly deferring the base class import to the bottom of the file via ghost
references, but Python requires base class imports before the class definition.
Ghost references for extended (base class) types are now skipped so their imports
remain at the top of the file.