问题：枫教授在一所大学教数学，他发现了一个函数，用于获得一个表达式的操作数的目的，函数命名op(i,e)可以描述如下:(problem:Professor Maple teaches mathematics in a university. He have invented a function for the purpose of obtaining the operands from an expression. The function named op(i,e) can be described as follows:)