The `extra_context` argument to `ModelAdmin.changeform_view`,
`add_view`, `change_view`, `changelist_view`, `delete_view`, and
`history_view` is used to pass extra context variables to a template, so
all of these arguments should have type `Optional[Dict[str, Any]]`.
Instead, these are currently typed as `Optional[Dict[str, bool]]`,
`Optional[Dict[str, str]]`, or `None`.
* Allow List[Tuple[Any]] as args_generator argument to format_html_join
format_html_join's args_generator argument can be anything that contains
tuples of things that can be coerced to strings or that have a
`__html__` method.
Fixes#721.
* Use `Iterable[Iterable[Any]]` as `args_generator` type
* Run linter
* Fix annotation of ModelAdmin.get_object
The type annotation in django-stubs indicated that the type of the
`from_field` argument to `ModelAdmin.get_object` should be `None`. In
fact, `None` is the default value of that argument. If the argument is
not `None`, [it is passed to a model's `_meta.get_field` method][impl], which
takes an argument of type `Union[Callable[..., Any], str`.
[impl]: https://github.com/django/django/blob/ac5cc6cf01463d90aa333d5f6f046c311019827b/django/contrib/admin/options.py#L767
* Fix formatting
rolandcrosby-check