Changes

: Remember we define the sum_times() function to add to time objects and return their sum? After we moved the function definition under the class definition in lab7d.py, it became a class function, and method for the time object. It can be invoked by using the Time.sum_times(t1,t2) syntax or t1.sum_times(t2) syntax. HowHowever, there is any also a way to invoke it by using a special function which ties to the '+' arithmetic operator.: The '+' operator is bind bound to the special function of an object's __add__() method. If we attached the same code we have for the sum_times() function to the special function __add__() for the time object, the we can use the '+' operator to tell the python interpreter to perform sum operation on thw the time object.

: Let's add the appropriate code to the __add__ function to overload the '+' operator so that we can use an arithmetic expression to tell the python interpreter to add two time objectobjects.