Python 3.6.6 (v3.6.6:4cf1f54eb7, Jun 27 2018, 03:37:03) [MSC v.1900 64 bit (AMD64)] on win32 Type "copyright", "credits" or "license()" for more information. >>> ============= RESTART: D:\CSI33F19\Python3\Chapter4\ListNode.py ============= >>> from ListNode import ListNode >>> n3 = ListNode(3) >>> n3.item 3 >>> n3.link >>> print(n3.link) None >>> n2 = ListNode(2, n3) >>> n2.link >>> int(0x000001E8F880CA58) 2100113230424 >>> id(n3) 2100113230424 >>> n1 = ListNode(1, n2) >>> n1.link >>> n1.link.item 2 >>> n1.link.item 2 >>> n1.link.link.item 3 >>> n1.link.link.link >>> n25 = ListNode(2.5, n2.link) >>> n25.link >>> id(n3) 2100113230424 >>> hex(id(n3)) '0x1e8f880ca58' >>> n2.link = n25 >>> n2.link.item 2.5 >>> n2 >>> n1.link >>> n1.link = n25 >>> n2 >>> n1.link >>> n25 >>> del n2 >>> n2 Traceback (most recent call last): File "", line 1, in n2 NameError: name 'n2' is not defined >>>