Function is_unionable

crates/vm/src/builtins/union.rs:196–203

(obj: PyObjectRef, vm: &VirtualMachine)

}

fn is_unionable(obj: PyObjectRef, vm: &VirtualMachine) -> bool {
    let cls = obj.class();
    cls.is(vm.ctx.types.none_type)
        || obj.downcastable::<PyType>()
        || cls.fast_issubclass(vm.ctx.types.generic_alias_type)
        || cls.is(vm.ctx.types.union_type)
        || obj.downcast_ref::<TypeAliasType>().is_some()
}

fn type_check(arg: PyObjectRef, vm: &VirtualMachine) -> PyResult<PyObjectRef> {
    // Fast path to avoid calling into typing.py