def reformat_language_tuple(langval):
    """Produce standardly-formatted language specification string using given language tuple.

    :param langval: `tuple` in form ('<language>', '<language variant>'). Example: ('en', 'US')
    :return: `string` formatted in form '<language>-<language-variant>'
    """
    if langval:
        langval_base, langval_variant = langval
        if langval_variant:
            langval_base = '{0}-{1}'.format(langval_base, langval_variant)

        return langval_base
    else:
        return None