Type Alias _D<T, $O>

_D: T extends object
    ? IdentityEqual<
        T,
        {},
        $ResolveBranch<$O, [$Then], T>,
        IsNever<
            keyof T,
            {
                $else: $ResolveBranch<$O, [$Then], T>;
                $then: $ResolveBranch<$O, [$Else]>;
            },
        >,
    >
    : $ResolveBranch<$O, [$Then], T>