python-3.x - [<__main__.state 对象位于 0x00D571C0>]

Question

我不断得到这个，[< main .state object at 0x00D571C0>]

我要打印 q

[Here I want to make a queue object. when I want to print q and the error comes. how to solve it?][1]

import numpy as np
start=np.array([[9,8,7],[6,5,4],[3,2,1]])

class state:
    def __init__(self,matno,parentno,mat):
        self.matno=matno
        self.parentno=parentno
        self.mat=mat
    def display(self):
        return f"matno:{self.matno},parentno:{self.parentno},mat:{self.mat}"

obj=state(1,0,start)
q=[]
q.append(obj)
print(q)