Calculates the total values for the inputed values.
        
        :return     <int>

def sum(self, values):
        """
        Calculates the total values for the inputed values.
        
        :return     <int>
        """
        values = sorted(values)
        try:
            return (values[-1] - values[0]).total_seconds()
        except IndexError, TypeError:
            return 0