Generating code for different versions of an api (to implement and host side by side)

[ShahOdin]

I have a service defined in smithy:

namespace smithy.foo
service Foo {
    version: "1"
}

later I make changes to this service and have:

namespace smithy.foo
service Foo {
    version: "2"
}

(How) can I generate code for both versions in a single project, so that I can have both apis implemented for the consumers to migrate from one to the other gracefully?