python算术运算符的扩展函数

test = 'ACM'
tests = '我是ACMER'
final = test + tests          #这里‘+’连接了test和tests两个字符串
number = 1000
newnumber = -number           #这里‘-’将number取负
index = [1,2,3,4]
index = index*3
print(final)                  #‘+’连接后的test+tests
print(newnumber)            
print(index)                  #‘*’倍数添入后的index