摘要：
00-- class, class object, instance object As shown below, Tracking is a class, and itself it's own class oject. in the object, __dict__ will have all 阅读全文
摘要：
00-- requirements a. to define a class of Point and a class of Line with Point as parent b. define a function in Line to calculate the lenth of 2 poin 阅读全文