code: def _select_sql(self, **kwargs):
          
          return 'SELECT {distinct}{modifier}{select}'.format(
                distinct='DISTINCT ' if self._distinct else '',
                modifier='{} '.format(' '.join(self._modifiers)) if self._modifiers else '',
                select=','.join(term.get_sql(with_alias=True, subquery=True, **kwargs)
                                for term in self._selects),
          )
docs: Overridden function to generate the SELECT part of the SQL statement,
          with the addition of the a modifier if present.