code: def req_string(self, model):
          
          if model not in self.models:
              model = self.models
          if self.min_ykver and self.max_ykver:
              return "%s %d.%d..%d.%d" % (model, \
                                             self.min_ykver[0], self.min_ykver[1], \
                                             self.max_ykver[0], self.max_ykver[1], \
                                             )
          if self.max_ykver:
              return "%s <= %d.%d" % (model, self.max_ykver[0], self.max_ykver[1])
  
          return "%s >= %d.%d" % (model, self.min_ykver[0], self.min_ykver[1])
docs: Return string describing model and version requirement.