python是一种面向对象进行编程的语言，对象的一个属性就是——方法（method）。这里以字符串为例，调用字符串自带的方法（method），来演示一个小例子。
search = '168'
num_a = '1386-168-0006'
num_b = '1681-222-0006'
print(search + ' is at ' + str(num_a.find(search)+1) + ' to ' + str(num_a.find(search)+len(search))+' of num_a.')
print(len(search))
print(search + ' is at ' + str(num_b.find(search)+1) + ' to ' + str(num_b.find(search)+len(search)) + ' of num_b.')
print(type(num_a.find(search)))运行结果是
168 is at 6 to 8 of num_a.
3
168 is at 1 to 3 of num_b.
<class 'int'>
Process finished with exit code 0