course_id = "AC2970Ta " title_code = "ACBCT 2970 Taxes and 7usiness Strategy" title_code
运行结果：
'ACBCTxa02970 Taxes and 7usiness Strategy'
course = title_code.strip(course_id) course
运行结果：
'BCTxa02970 Taxes and 7usiness Strategy'二.
course_id = "ACBCT 2970 " title_code = "ACBCT 2970 Taxes and 7usiness Strategy" course = title_code.strip(course_id) course
运行结果：
'axes and 7usiness Strategy'三.
course_id = "ACBa " title_code = "ABCaT 2970 Taxes and 7usiness Strategy" course = title_code.strip(course_id) course
运行结果：
'Txa02970 Taxes and 7usiness Strategy'四.
course_id = "ACBCT 2970 " title_code = "ACBCT 2970 Taxes and 7usiness Strategy 2829ABC" course = title_code.strip(course_id) course
运行结果：
'axes and 7usiness Strategy 28'理解(以三为例)：
1, 先把course_id 变成cour=[”A“,“C”,“B”,“a”]
2, 然后对 title_code 元素 X 进行从左（头）往右和从右（尾）往左依次对比cour中的元素 Y，如果X==Y，则删掉X,直到X！=Y为止，返回title_code 剩下的子字符串的copy(因为python的字符串是不可改变的)
正则
import re course_id = "ACB " title_code = "ACB Taxes ACB and S ACB trategy" course = re.sub(course_id,"",title_code,2) course
运行结果：
'Taxes and S ACB trategy'PS：数字二是从左往右删除的次数
如果只想删除开头的：
import re
course_id = "ACB "
title_code = "ACB Taxes ACB and S ACB trategy"
course = re.sub("^"+course_id,"",title_code)
course
或者：
course = re.sub(course_id,"",title_code,1) course
运行结果：
'Taxes ACB and S ACB trategy'
