Returns the time value at ``percent`` of this interval.

        :param percent: the percent
        :type  percent: :class:`~aeneas.exacttiming.Decimal`
        :raises TypeError: if ``time_point`` is not an instance of ``TimeValue``
        :rtype: :class:`~aeneas.exacttiming.TimeValue`

def percent_value(self, percent):
        """
        Returns the time value at ``percent`` of this interval.

        :param percent: the percent
        :type  percent: :class:`~aeneas.exacttiming.Decimal`
        :raises TypeError: if ``time_point`` is not an instance of ``TimeValue``
        :rtype: :class:`~aeneas.exacttiming.TimeValue`
        """
        if not isinstance(percent, Decimal):
            raise TypeError(u"percent is not an instance of Decimal")
        percent = Decimal(max(min(percent, 100), 0) / 100)
        return self.begin + self.length * percent