def buildSources(self, sourceTime=None):
        """
        Return a dictionary of date/time tuples based on the keys
        found in self.re_sources.

        The current time is used as the default and any specified
        item found in self.re_sources is inserted into the value
        and the generated dictionary is returned.
        """
        if sourceTime is None:
            (yr, mth, dy, hr, mn, sec, wd, yd, isdst) = time.localtime()
        else:
            (yr, mth, dy, hr, mn, sec, wd, yd, isdst) = sourceTime

        sources  = {}
        defaults = { 'yr': yr, 'mth': mth, 'dy':  dy,
                     'hr': hr, 'mn':  mn,  'sec': sec, }

        for item in self.re_sources:
            values = {}
            source = self.re_sources[item]

            for key in defaults.keys():
                if key in source:
                    values[key] = source[key]
                else:
                    values[key] = defaults[key]

            sources[item] = ( values['yr'], values['mth'], values['dy'],
                              values['hr'], values['mn'], values['sec'], wd, yd, isdst )

        return sources