Function create_speech_stream 

pub fn create_speech_stream<C, Fut, B, E>(
    client: C,
    request: &CreateSpeechRequest,
) -> CreateSpeechStream<Fut, B, E> 
where
    C: FnOnce(Request<String>) -> Fut,
    Fut: Future<Output = Result<Response<B>, E>>,
    B: Body,

Create speech