def alephalpha_modelname_to_contextsize(modelname: str) -> int:
    """
    Converts an Aleph Alpha model name to the corresponding context size.

    :param modelname: The name of the Aleph Alpha model.
    :return: The context size for the model.
    """
    if modelname not in LUMINOUS_MODELS:
        raise ValueError(
            f"Unknown model: {modelname}. Please provide a valid AlephAlpha model name."
            "Known models are: " + ", ".join(LUMINOUS_MODELS.keys())
        )

    return LUMINOUS_MODELS[modelname]

    Converts an Aleph Alpha model name to the corresponding context size.

    :param modelname: The name of the Aleph Alpha model.
    :return: The context size for the model.
    
llama-index-integrations/llms/llama-index-llms-alephalpha/llama_index/llms/alephalpha/utils.py