code: def getPrioritySortkey(self):
          
          priority = self.getPriority()
          created_date = self.created().ISO8601()
          return '%s.%s' % (priority, created_date)
docs: Returns the key that will be used to sort the current Analysis
          Request based on both its priority and creation date. On ASC sorting,
          the oldest item with highest priority will be displayed.
          :return: string used for sorting