code: def process_ticket(self):
          
          try:
              proxies = []
              if self.allow_proxy_ticket:
                  ticket = models.Ticket.get(self.ticket, self.renew)
              else:
                  ticket = models.ServiceTicket.get(self.ticket, self.renew)
              try:
                  for prox in ticket.proxies.all():
                      proxies.append(prox.url)
              except AttributeError:
                  pass
              if ticket.service != self.service:
                  raise ValidateError(u'INVALID_SERVICE', self.service)
              return ticket, proxies
          except Ticket.DoesNotExist:
              raise ValidateError(u'INVALID_TICKET', self.ticket)
          except (ServiceTicket.DoesNotExist, ProxyTicket.DoesNotExist):
              raise ValidateError(u'INVALID_TICKET', 'ticket not found')
docs: fetch the ticket against the database and check its validity
  
              :raises ValidateError: if the ticket is not found or not valid, potentially for that
                  service
              :returns: A couple (ticket, proxies list)
              :rtype: :obj:`tuple`