Function use_completion 

pub fn use_completion(options: CompletionOptions) -> UseCompletionState

Create a completion interface

Example

let mut completion = use_completion(CompletionOptions {
    provider: "openai".to_string(),
    api_key: "sk-...".to_string(),
    model: "gpt-4o-mini".to_string(),
    ..Default::default()
});

completion.complete("Translate 'hello' to Spanish");