What is the use of writing Jiange in the third paragraph of Shu Dao Nan?

The poet described a political situation from the danger of Jiange. He borrowed the phrase "the victory lies in the shape, but the bandits don't live together" from Zhang Zai's Ming of Jiange in the Western Jin Dynasty, aiming to persuade people to take warning and be alert to the occurrence of war. Combining with the social background at that time, he revealed that "the tiger's teeth are sharp, and the wolf in Shu" was not only a pun on the beasts of Shu, but also an allusion to political darkness, expressing his worries and worries about national affairs.