Return enforced ascii string
        éko=>ko

def force_ascii(value):
    """
        Return enforced ascii string
        éko=>ko
    """
    if not isinstance(value, (str, unicode)):
        return unicode(value)
    if isinstance(value, unicode):
        return unidecode.unidecode(value)
    else:
        return unidecode.unidecode(force_unicode(value))