Hi,
it would be really cool to have a feature to define common namespaces for structs using serde. Something like this:

#[derive(Serialize, Deserialize)]
#[namespace(F,foourn)]
struct Foo {
  id: String,
  #[serde(flatten)]
  #[namespace(B,barurn)]
  bar: Bar
}

#[derive(Serialize, Deserialize)]
struct Bar {
  name: String,
  desc: String
}

resulting in:

<F:foo xmlns:B="foourn" xmlns:F="barurn">
      <F:id>123</F:id>
      <B:name>asdf</B:name>
      <B:desc>foobar </B:desc>
</F:foo>

Background

I sometimes face (old) API's that requrie XML to be structured in a way similar to the given example. They use namespaces to distinguish between entities to form some sort of inheritance tree.
A feature like this would make interacting with these kind of API's very easy.