About python class constant and scope

class Hoge:
    PRIORITY = 1
    def hoge(self,p=PRIORITY, priority=4): # not self.PRIORITY
        print(self.PRIORITY,p,priority)

print(Hoge.PRIORITY) # could not use PRIORITY
r = Hoge()
r.priority = 7
r.hoge()
r.hoge(3)
r.hoge(3,5)
r.hoge(2)
print(Hoge.PRIORITY,r.priority) # could not use PRIORITY

1
1 1 4
1 3 4
1 3 5
1 2 4
1 7