You need to implement addition, subtraction, multiplication and division. Provide a reasonable number of tests. Your program should be able to cope with addition, subtraction, multiplication, division and composition of functions. Provide auxiliary functions to simplify such expressions. Provide reasonable test cases.
Phone trees can have problems if people are unavailable.
Your job is to build an algorithm that will build a robust phone tree. Write a program that will take a list of names and phone numbers and produce for each such pair a sheet of instructions and a list of people to call.