'Return this block\'s date in a human-readable format. If the date
is None, returns the empty string.'

@property
def relative_datestring(self):

    if (self.date is None):
        return ''
    locale = to_locale(get_language())
    delta = (self.date - datetime.datetime.now(utc))
    try:
        relative_date = format_timedelta(delta, locale=locale)
    except KeyError:
        relative_date = format_timedelta(delta)
    date_has_passed = (delta.days < 0)
    date_format = (_(u'{relative}    ago    -    {absolute}') if date_has_passed else _(u'in    {relative}    -    {absolute}'))
    return date_format.format(relative=relative_date, absolute='{date}')
