Type Alias UserContentResolver 

pub type UserContentResolver = dyn Fn(&ValueWord) -> Option<ContentNode> + Send + Sync;

Optional user-defined Content impl resolver.

When set, render_as_content calls this function before falling through to built-in dispatch. If the resolver returns Some(node), that node is used. The resolver is typically set by the VM executor to check for user-defined impl Content for MyType { fn render(self) -> ContentNode } blocks.