Who knows the genre of Shu Dao Nan written by Li Bai? What kind of long poem is it?

The difficulty of Shu Dao is an old topic in ancient Yuefu. Li Bai's poem is a seven-character Yuefu. It is a magnificent farewell poem, describing boldness. It uses bold exaggeration, absurd imagination and artistic atmosphere of sighing, strengthens the emotion expressed in the poem and deepens the content layer by layer.