Task $1$: To implement priority scheduling, you will first need to do the following:

$(1)$ Add a variable in struct proc to indicate the nice level of a process. Use a range

of $0$ to $20,$ with $20$ being the lowest and $0$ the highest priority.

$(2)$ Determine the default priority of a process when it is created and add the code to

do so$.$ Usually, it is somewhere in the middle of the range.

$(3)$ Implement a system call:

int setnice$($int pid, int n$)$;

to change the nice value of process pid to n$.$ The returned value should be the

original nice value of this process.

$(4)$ Implement a second system call:

int getnice$($int pid$)$;

that returns the nice value of a process.