C++ code of example 4.11 in the course ROSBasicsIn5Days

Course Support ROS Basics In 5 Days (C++)
1 
~ FibonacciAction(void)

{

}

Why are there lines of code like above in this example? How does it work and what is this part for?

Thank you.

2

Thats the detsructor in C++.
Its called everytme you detsroy the class Fibonacci ( ths is done when you close the program basicaly ).
In this case you dont do enything, but normally here you would clean up varables, save files and thngs like that.