def doc_label_name(context_type):
    """
    Takes a string `context_type` and makes that a standard 'label' string.
    This functions is useful for figuring out the specific label name in 
    metadata given the context_type.

    :param context_type: A type of tokenization.
    :type context_type: string

    :returns: label name for `context_type` as string.
    """
    return str(context_type) + '_label'