code: def get_host(self, domain_part):
          
          if self.map.host_matching:
              if domain_part is None:
                  return self.server_name
              return to_unicode(domain_part, 'ascii')
          subdomain = domain_part
          if subdomain is None:
              subdomain = self.subdomain
          else:
              subdomain = to_unicode(subdomain, 'ascii')
          return (subdomain and subdomain + u'.' or u'') + self.server_name
docs: Figures out the full host name for the given domain part.  The
          domain part is a subdomain in case host matching is disabled or
          a full host name.