For custom converters, we can now choose if they should be mandatory or optional.
Up to now, they were only optional.
This is an API-breaking change. So if you'd like to update old (<`0.8.0`) code, you need to change this:
python3
type_checked_constructor(converters={'foo': conv_foo})
dataclass
class Foo:
foo: ...
to that:
python3
type_checked_constructor(converters={'foo': optional_converter(conv_foo)})
dataclass
class Foo:
foo: ...
because the default (and only) behavior of converters was to be optional.
Now, there is a new option to use `optional_converter` instead.