Function build_model 

pub fn build_model(
    config: ModelConfig,
    store: WeightStore,
    gpu: Box<dyn GpuBackend>,
    max_batch_tokens: usize,
    kv_block_size: usize,
    max_seq_len: usize,
    max_batch_size: usize,
    mtp_quant: MtpQuantization,
    use_speculative: bool,
    prefix_cache: Box<dyn PrefixCache>,
    mtp_vocab_size: u32,
    comm: Option<Arc<dyn CommBackend>>,
    self_speculative: bool,
    num_drafts: usize,
    kv_dtype: KvCacheDtype,
    inference_reserve: usize,
    gpu_memory_utilization: f64,
    ssm_cache_slots: usize,
    layer_dtypes: Vec<KvCacheDtype>,
    ssm_checkpoint_interval: usize,
    hss_cache_blocks_per_seq: Option<u32>,
    dflash_args: Option<DflashBuildArgs<'_>>,
    lora_args: Option<LoraBuildArgs<'_>>,
    nllb_lang: Option<(u32, u32)>,
    nllb_lora_dir: Option<PathBuf>,
) -> Result<Box<dyn Model>>