Exercise about passing variable TO the and OUT of the function
(all vars int)

How to pass the variable in general ways?

1.
Lets have variable int a = 2

1.5. Write a function (int ch(int i) eg. int ch(7)) that changes variable by assigment of return value and proves this change by print

1.6. Write a function that changes input variable by "out" params and proves this change by print

1.7. Write a function that changes input variable by "reference"  
params a prove this change by print