code: def create_css(self, fileid=None):
          
          if fileid:
              rules = self._rules.get(fileid) or []
          else:
              rules = self.rules
  
          compress = self._scss_opts.get('compress', True)
          if compress:
              sc, sp, tb, nl = False, '', '', ''
          else:
              sc, sp, tb, nl = True, ' ', '  ', '\n'
  
          scope = set()
          return self._create_css(rules, scope, sc, sp, tb, nl, not compress and self._scss_opts.get('debug_info', False))
docs: Generate the final CSS string