Macro pyobject_native_type 

#[doc(hidden)]
macro_rules! pyobject_native_type {
    ($name:ty, $layout:path, $typeobject:expr, $type_hint_module:expr, $type_hint_name:expr $(, #module=$module:expr)? $(, #checkfunction=$checkfunction:path)? $(;$generics:ident)*) => { ... };
}

Declares all of the boilerplate for Python types which can be inherited from (because the exact Python layout is known).