In this lab, you will practice writing leaf procedures. A skeleton code is provided for you to write a program which will calculate the Fibonacci sequence $(0,1,1,2,3,5,8,....).$ The first n number will be shown as the output, where n will be given by the user. As the first two numbers $(0$ and $1)$ are predefined in a Fibonacci sequence, n must be $>=3.$ Otherwise, the program will show an error message. The skeleton program uses two leaf procedures:

$$ print$\_$number: this procedure prints an integer followed by a space character.

$$ add$\_$two: this procedure does the addition of two integers, save the result in $s$0,$ and return the value of $s$0$ to the caller.